Technical Service-Electronic product solution company-Electronic and electrical product development-Bluetooth design-S

Technical Service

07-10

2023

Product Show—SNC27P168

SNC27P168 is a single-channel speech synthesis IC with 12-bit PWM direct-drive circuit, which integrates one input port and 16 I/O ports into a 4-bit microcontroller. Through the programming of the microcontroller in the SNC27P168, various applications of the user, including the synthesis of voice parts, the setting of key triggers, output control and other logic functions, can be easily realized.Working voltage: 2.1V~5.1VSystem clock: 2.304MHz +-1.5%Voice duration: 168sec@6KHzRAM size: 128*4 bitMaximum program space 64K*12 bitI/O ports:- Input port P9.0, shared with reset pin- 16 I/O ports : P1, P2, P3, P6- High drive/reverse current : P2, P3, P6- Normal drive/reverse current : P1timer:- Timer 1: 2ms/4ms- Watchdog Timer (WDT): 110msIR output: P2.3 or P1.38 groups of hardware PWMIO: P2,P3,P6 - P3/P6 share the same PWMIOLow Voltage Reset (LVR)- Typical 1.9V Enable Disable Option- Low LVR current when low voltage reset (LVR) occursLow Voltage Detection (LVD)- 2 levels: 2.2V , 3.2V
07-09

2023

Car bluetooth phone technology

Research and Implementation of Car Bluetooth Telephone TechnologyThe car bluetooth phone is specially designed for driving safety and comfort. Users only need to have a mobile phone with bluetooth function to connect with the car bluetooth, so as to make calls through the car equipment. Users do not need to touch the mobile phone to control the mobile phone, use voice commands to control, operate the vehicle terminal or even the steering wheel to answer or make calls, and make calls through the car audio or Bluetooth wireless headset, which can ensure a good call effect. Car bluetooth phones are generally used in front-mounted car entertainment terminals and rear-mounted car devices, and it is an applicable technology. This paper mainly introduces the realization principle of the Bluetooth phone function of the vehicle-mounted device based on the Android system.1. Bluetooth architecture of Android systemAndroid system Bluetooth includes application layer, framework layer and local library, HAL layer and Kernel kernel driver code. The BlueZ protocol is mainly implemented in the local library and kernel code, and the local library and kernel communicate through the HAL layer interface. The framework layer mainly implements the management of the Bluetooth application protocol Profile, and interacts with the local library through the JNI interface. The framework layer includes local Bluetooth device adaptation, local Bluetooth information and management, remote device attributes, RFCOMM-based Bluetooth device server and client socket management, various Bluetooth profile services, etc. The modules that manage Bluetooth phone functions include SettingsApp, Phone, and Bluetooth. It is mainly the Android system of the vehicle-mounted smart device that supports the Bluetooth HFP protocol (Hands-freeProfile). HFP can realize the phone control function based on the Bluetooth connection, and provide a unified standard for the Bluetooth phone function.2. Realization of Bluetooth phone in Android system2.1 Bluetooth HFP protocolThe HFP protocol defines two roles: the audio gateway (AG) and the hands-free component (HF): the AG device is used as the audio input/output gateway, that is, the mobile phone terminal; the HF device is used as the remote audio input and output mechanism of the audio gateway, that is, the vehicle device end. The HFP protocol provides a number of telephone-related remote control functions for HF devices. First, establish RFCOMM connections, and exchange AT commands between the two devices through the RFCOMM protocol channel. The AT command set is based on ITUTV. 250 and GSM07.07. The HF end sends AT commands to read the AG end status and control the AG end phone functions. At the same time, the AG side indicates the status of the terminal through the AT command (+CIEV:).2.2 Realization of Android system HF protocolThe AG side of the Android system HFP protocol receives and parses the call-related AT commands and processes the calls to the phone system interface. AT commands include:"AT+D" dialing operation; "AT+A" answering operation; "AT+CHUP" hanging up operation; "AT+CLCC" call status query; "AT+VTS" dual-tone multi-frequency tone sending; "Call hold operation; "AT+VGS" speaker volume adjustment; "AT+VGM" microphone volume adjustment; "+CIND" mobile phone status indication, etc.It meets all the phone control functions of the HF end. Therefore, the Android system mobile phone supports the AG-side Bluetooth headset and Bluetooth phone functions, and the HF-side vehicle equipment should also have equivalent functions. The vehicle device side needs to increase the interface interaction and logic processing of the Bluetooth phone, and support the processing flow of the HF side of the HFP protocol.The framework layer (Framework) above Android 5.0 adds hands-free service client management and improves the HFP protocol process processing, so the vehicle-mounted equipment using Android 5.0 and above systems can provide complete Bluetooth phone functions on the basis of the existing framework. The specific implementation process is shown in Figure 1.BluetoothClientService adds phone control-related interfaces, including dial0, acceptCall(), holdCall0, terminateCall(), holdcau0, getCurrentCalls0, etc., providing functions such as dialing, answering, hanging up, holding, and call status query. HeadsetClientStateMachine, as a bridge between the framework layer and protocol processing, mainly completes the logic processing and state jump of HFP in the framework layer, including the following two aspects: (1) Receive phone instructions from the local protocol layer module, and notify the application through system broadcast The program rings or updates the call status display. (2) Manage the status of the protocol (connected or disconnected), call this interface, and send the control of the application to the protocol module. In the Bluetooth protocol layer, Bta-hf-client-cmd is responsible for the assembly and transmission of AT commands, and Bta_hfclient is responsible for the reception, analysis and reporting of AT commands. The Bluetooth phone APP is mainly responsible for UI interaction and interface logic processing, and provides users with convenient functions, including dial pad, synchronous address book and call records, search contacts, call reminders, buttons on the call interface, etc. If a phone function button is added to the steering wheel, the button event of the steering wheel is sent to the vehicle-mounted device through the vehicle wiring harness, and functions such as calling, answering, and hanging up can be triggered, so that the driver can control the mobile phone without leaving the steering wheel. .SummarizeAt present, Bluetooth devices are widely used, and the Bluetooth protocol is relatively mature. It is a form of vehicle interconnection to transfer the functions of mobile phones to vehicle-mounted devices through Bluetooth connections. The purpose is to facilitate driving and improve user experience. With the development of hardware and software technology, more electronic products based on Bluetooth connection solutions will be applied to vehicle, medical and health fields, providing users with more convenience.The above is the research and implementation method of the car Bluetooth phone technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
07-09

2023

Product Show—SN8F5705

SN8F5705 is compatible with MCS-51 instruction set eight-bit microcontroller, and under the same execution frequency standard, its efficiency can reach up to 12.1 times of the original 8051. At the same time, the operating voltage range (1.8 V to 5.5 V) and operating temperature (-40°C to 85°C) are expanded through advanced semiconductor technology, allowing the product to operate at high speed in various applications.In this microcontroller, built-in 16 KB ROM, 256 bytes IRAM and 1 KB XRAM. With the assistance of the hardware multiplication and division unit (MDU), complex mathematical operations can be greatly accelerated. In addition, the microcontroller also has 12-bit high-precision ADC, 2 sets of operational amplifiers (OP-Amp), 2 sets of comparator circuits, 3 sets of PWM generators, 3 sets of 16-bit counters (timers) and UART, SPI, I2C communication interface to meet the application occasions of consumer electronics products, home control, brushless motor control, etc.Shenzhen Zuchuang Microelectronics is the first-level agent of Songix in mainland China. It sells Songix single-chip microcomputers and voice ICs, and can provide technical support for Songix solutions. It can also directly develop and design electronic products for customers. It has a wealth of experience. Experience in hardware development and program design can help customers quickly develop products and put them on the market as soon as possible.SN8F5705.pdf
07-08

2023

SCM touch sensing technology

Single-chip touch sensing technology is a technology widely used in electronic devices and embedded systems to realize the interaction and control between users and devices. It detects the touch action of the human body, converts the touch signal into an electrical signal, and processes and responds through the single-chip microcomputer.The main principle of touch sensing technology is based on the detection of capacitance changes. When a human body approaches or touches a surface with sensing electrodes, it causes a change in capacitance. This change can be detected and measured by a capacitive sensor. Commonly used touch sensing technologies include capacitive touch and resistive touch.In capacitive touch technology, capacitive sensors are usually composed of conductive materials such as ITO (indium tin oxide)-coated glass or polymer films. When the human body approaches or touches the capacitive sensor, a capacitive coupling is formed between the human body and the sensor. The microcontroller detects touch events by measuring changes in capacitance and converts them into digital signals for processing.Resistive touch technology is based on a change in resistance at the point of touch. The touch screen is usually composed of two layers of transparent conductive film. When the touch point touches the conductive film, the resistance between the two layers of conductive film will be changed. The single-chip microcomputer detects the touch event by measuring the change of the resistance, and performs corresponding processing and responseIn the single-chip microcomputer touch sensing technology, the single-chip microcomputer plays an important role. It is connected with the touch sensor through the interface circuit to obtain the electrical signal generated by the sensor. The microcontroller then samples, filters, and processes these signals to determine the occurrence and location of touch events. Once a touch event is detected, the microcontroller can perform corresponding operations, such as controlling the content of the display, adjusting the volume, switching menus, etc.Single-chip touch-sensing technology is widely used in modern electronic devices, such as smartphones, tablet computers, car navigation systems, and home appliance control panels. It provides an intuitive and convenient user interface that enables users to operate and control it through a touch screen or touch panel without the need for additional physical keys or controllers.In addition, MCU touch sensing technology also has some advantages, such as fast response time, high sensitivity, good durability, easy integration and high flexibility. These advantages make single-chip touch-sensing technology one of the commonly used interactive methods in modern electronic devices.During the development and application of single-chip touch-sensing technology, there are several key aspects to consider:Sensor design and layout: Select the appropriate touch sensor type (such as capacitive or resistive) and material, and do a suitable sensor layout. Sensor design and layout can affect touch sensitivity, accuracy, and reliability.Signal collection and processing: The single-chip microcomputer needs to collect the electrical signal output by the sensor, and perform appropriate filtering, amplification and digital processing on it. This includes the choice of sampling rate, the design of filtering algorithms, and the implementation of signal processing algorithms.Touch event detection algorithm: Through the analysis and processing of sensor signals, it is necessary to design and implement a touch event detection algorithm. These algorithms can be based on techniques such as threshold determination, edge detection, and pattern recognition to determine the occurrence and location of touch events.Response and interaction design: According to the detection result of the touch event, the microcontroller needs to perform corresponding operations and interactions accordingly. This may include changing the display, adjusting the volume, executing functional commands, etc. Responsive and interactive design needs to consider user experience and interface friendliness.System stability and reliability: Single-chip microcomputer touch sensing technology needs to have stability and reliability in practical applications. This includes design for suppression of noise and interference, adaptability to temperature and humidity, and power management.Integration and scalability: MCU touch sensing technology usually needs to be integrated with other system components, such as display screen, sound output, communication interface, etc. Interface protocols, communication protocols, and software development interfaces (APIs) need to be considered during design in order to achieve functional expansion and system flexibility.In short, single-chip touch-sensing technology realizes a convenient and intuitive user interaction method by detecting and responding to human touch actions. It is widely used in modern electronic devices, and with the advancement and innovation of technology, it will continue to develop and evolve to provide users with a more intelligent and convenient interactive experience.
07-07

2023

DDR High Speed Circuit PCB Design

DDR high-speed line PCB design refers to the use of specific PCB (Printed Circuit Board, printed circuit board) design technology to achieve high-speed signal transmission when designing computer memory modules (such as DDR, DDR2, DDR3, DDR4, etc.). DDR (Double Data Rate) memory is a high-speed random access memory that can transmit two data points per clock cycle. In order to ensure the normal operation of DDR memory, special PCB design techniques must be adopted to deal with issues such as high-frequency signals, signal integrity, and electromagnetic interference.In the design of DDR high-speed line PCB, the following aspects are the key points to be considered:Length matching and delay control: The signal transmission speed on the DDR memory bus is very fast, so it is necessary to ensure that the lengths of the data and control lines match to prevent timing problems caused by different arrival times of the signals. In addition, by controlling the delay of the signal, the signal can reach the target device within the same clock cycle, so as to improve the performance of the system.Power supply and ground lead planning: In DDR high-speed line PCB design, good power supply and ground lead planning is very important. By properly planning the positions of the power supply and ground leads, electromagnetic interference and signal crosstalk can be reduced, and signal integrity can be improved.Signal integrity: The high-speed signal transmission of DDR memory requires high signal integrity. Therefore, in the PCB design process, technologies such as impedance matching, signal echo reduction, reasonable layout and wiring, and separation of signal and power layers are required to ensure signal stability and reliability.Interlayer interconnection and signal layer allocation: DDR high-speed lines usually adopt multi-layer PCB design to realize interlayer interconnection and signal layer allocation. Through reasonable layer stacking and signal layer allocation, signal crosstalk, electromagnetic interference, and transmission delay can be reduced, and system performance can be improved.Differential signal design: DDR memory uses differential signals to transmit data, so the layout, matching and routing of differential pairs need to be properly handled in PCB design. Differential signal design can improve anti-interference ability and transmission speed.In short, DDR high-speed line PCB design is a complex task, and factors such as signal integrity, timing requirements, electromagnetic compatibility, and anti-interference ability need to be considered comprehensively to ensure the stability and reliability of the DDR memory system.
07-05

2023

Hardware Design Process

The development process of a product is a complicated and highly technical job, and a stable and reliable hardware platform with excellent performance is the foundation and guarantee of the company's product quality. Therefore, the process of hardware design work should follow certain standards and norms in order to meet the requirements of quality assurance. This paper focuses on the specification process of hardware design. It mainly includes the following contents: confirmation of hardware requirements, hardware system design, schematic diagram design, PCB design, prototype joint debugging and testing, project review and case closing.1. Confirmation of hardware requirementsBefore developing a product, first confirm the hardware requirements of the product. This information is usually provided by the customer in a very detailed document, and the business department of the company conveys the requirements to the development department. It is very important to understand user needs, because subsequent product solution selection, development plans, product inspection standards and other information come from this. This information includes: the target market for product application; all functions and performance standards that need to be met; the appearance size, mold and accessories of the product; the time of product demand.2. Hardware system designHardware system design, including selection of overall solution; confirmation of product mold appearance; formulation of project plan. According to customer needs, such as CPU processing power, storage capacity and speed, function and interface requirements, etc., select the appropriate overall solution. And to complete the selection of design schemes for key functional modules, the selection of key components, technical data, technical channels and technical support, fully consider technical feasibility, reliability and cost control. The selection of key components should follow the following principles:Unity: key function module devices, in the case of meeting the functional and performance requirements, try to choose module devices that have been used in other solutions within the company, and try to ensure the unity of peripheral circuits.Versatility: Try to choose pin to pin compatible components with a wide variety of components, as well as chips that have been widely used and verified in the market, and try to avoid choosing unpopular chips to reduce design risks.High cost performance: In the case of meeting the demand, try to choose low-cost components.Convenient procurement: Try to choose components that are convenient to purchase, have a short delivery period, and have no plans to stop production. The selection and design of molds should be as far as possible from the user's point of view, aesthetics, durability, safety, heat dissipation, cost, etc. are all issues that need to be considered. This work needs to be completed jointly by hardware engineers, structural engineers and art engineers. A realistic and rigorous project plan is a guarantee for product development in terms of time and efficiency. The project plan should not only take into account various uncertain factors that may arise, reasonably arrange the time schedule of each stage, but also ensure the work efficiency of the project personnel during the development process, so as to ensure that the product development is within the time required by the customer, and the quality and quantity are guaranteed in advance the completion.3. Schematic designThe design of the schematic diagram is fundamental to ensure the logical correctness of a product hardware. If there is a problem with the schematic design, it will cause the performance of some functional modules of the product to deteriorate or fail, and the system will be unstable or even unable to work if it is serious. The things to pay attention to in schematic design are roughly summarized as follows:When drawing the schematic diagram, try to use the company's standard component library package, and try to use the company's unified plan for the general function module design. The standardized schematic diagram design is easier to manage and review, and facilitates procurement and production control.General rules for schematic diagram design: According to the target market, determine the protection level of the schematic diagram for the part of the circuit that needs to be protected.Power supply system: At the beginning of the design, it is necessary to analyze in detail the current size required by each power supply in the board, accuracy requirements, ripple control, power-on sequence, etc. The design of the power supply must have sufficient margin, otherwise it will easily cause problems such as excessive heat generation of the power chip, insufficient output capacity of the power module, and malfunction of the system. Attention should also be paid to the separation of digital power and analog power.Cost control: Generally speaking, the greater the redundancy in the design, the more reliable the system will be, but the higher the cost will be; conversely, the smaller the redundancy will be, the lower the cost will be but the lower the reliability will be. The first version of the schematic diagram can reserve high design redundancy to ensure the stability of the system. At the same time, some compatible designs can be made to facilitate the cost reduction test in the subsequent debugging process, and finally achieve the most appropriate redundancy to make the product more cost-effective. optimize.Review: After the schematic design is completed, it needs to be sent to the chip provider for review, and the key modules are sent to the chip manufacturer for technical support review. The company should also organize strict review, especially for newly added functional modules, carefully review and demonstrate, in order to Ensure the correctness of the schematic diagram.Write design documents: 10-port connection methods related to software debugging, control status requirements, device addresses connected to the bus, etc., to facilitate subsequent software debugging.BOM production: Export the list of components, and make a BOM list according to the company's BOM standard format, indicating the code, type, detailed description, accuracy level, package size, assembly method, single-machine consumption, and bit number of each device. After completion, submit the sample plan quantity to the relevant personnel to check the inventory, and submit the purchase requisition if there is a shortage of materials. This part of the work should be done in advance, so as not to affect the development cycle due to the arrival time of materials.4. PCB designAfter the schematic diagram is completed, export the netlist and synchronize it to the PCB file. The packaging of PCB B should adopt the company's standard packaging as much as possible, and the new device packaging should read the chip manual carefully. Before starting PCB drawing, first ensure the correctness of all component packages.1. General steps and precautions of PCB designAccording to the selected mold, confirm the size of the motherboard, the position of all connectors related to mold assembly, height restrictions, areas where devices are prohibited, etc.Layout: The first principle of layout is to ensure the routing rate of the wiring, and place the devices of certain functional modules together as much as possible, but the interconnection between chips should pay attention to which devices should be placed close to which chip; digital devices and analog devices should be Separate and keep as far away as possible; heat-sensitive devices should be placed away from heat-generating devices; devices and wiring should not be placed near the positioning holes; decoupling capacitors should be as close as possible to the V c C of the device; when placing devices, consider subsequent debugging and soldering, not too dense; Consider the aesthetics of the entire board.2. General rules for wiringClock line and high-speed signal line: clock line and high-speed signal line are generally easy to be the interference source of electromagnetic radiation, so special attention should be paid to wiring. Generally divided into single-ended and differential. Generally, the single-ended line should be as short as possible, the formation or reference layer should be as complete as possible to reduce the loop, the ground cover should be complete and more ground holes should be drilled; the differential line should be complete in formation or reference layer, with equal length and equal distance. If there is an impedance requirement, the line width and line spacing should be calculated to reduce radiation.Important signal lines: pay attention to the treatment of ground cover, formation integrity and impedance control.Power line: According to the evaluation of the current of each power supply, the thickness of each power line can be set. Generally, the power line should be as thick as possible. The greater the current, the thicker the power line.Ground wire: To ensure the integrity of the ground plane as much as possible, the ground wire should be as thick as possible.Design inspection and review: After the P4 design is completed, use the inspection function that comes with the tool to check the spacing and connectivity to ensure that the spacing and connectivity are correct. Finally, after self-checking and optimization, send it to the chip provider to check the design, and send important modules to Corresponding technical support checks must also be carefully reviewed item by item within the company in accordance with standard procedures.Template file output and production: After the PCB design is completed, a board-making instruction file must be produced, including board thickness, board material, surface treatment method, characters, solder mask, board size and whether to assemble boards, quantity, impedance, etc. There will be a company's standard format for printed board factory production. At the same time, provide BOM files, coordinate files and silk screen drawings to the chip factory for sample mounting and welding.5. Sample joint debugging and testing1. Model joint debuggingAfter the hardware schematic diagram is designed, provide the schematic design document to the software personnel, so that they can start modifying the software according to their own hardware design in advance. After the sample mounting is completed, the software personnel will be handed over to the final software development work. During this period, the necessary hardware debugging will be carried out in cooperation with the software work. After all the functions required by the customer are completed, the hardware engineer will complete the remaining testing and confirmation. Work.2. Sample testTesting work can generally be divided into functional testing, performance testing and debugging, on-site testing and customer confirmation, and third-party certification testing.Taking the hardware requirements confirmation document as a guiding document, according to the requirements put forward by customers, hardware engineers conduct detailed tests and confirmations on all required functions and performance requirements, and perform software and hardware debugging for projects that do not meet the standards. The performance indicators not proposed by the customer are based on the relevant national standards and company testing standards.After the hardware engineer's testing and debugging is completed, it is submitted to the company's internal testing, and the group does a confirmation test to confirm whether the product meets all standard requirements in the laboratory. Due to the possible complexity and particularity of the target market environment, after the product self-test is completed, testers need to go to the target market site to conduct on-site multi-site testing. At the same time, communicate with customers to allow customers to make final confirmation of the product. According to customer requirements, if a third-party certification body is required to test, a prototype needs to be provided to the third-party certification body for certification testing and a certification report.6. Project review and closingOrganized by the project manager, the participants include the company's technical director, business personnel, software chief designer, hardware chief designer, testers and related senior technical personnel. Taking the technical requirements provided by customers as the guiding evaluation standard, and based on various internal design standards, testing standards, and auditing standards of the company, we conduct rigorous and detailed audits on various design documents, test reports and customer feedback of the project. Under the premise of ensuring that the product fully meets the customer's needs, evaluate and review the correctness, rationality, standardization, reliability and cost-effectiveness of the product design, and confirm whether the project meets the requirements and the case can be closed, and the relevant personnel participating in the project review Personnel sign and confirm one by one.Judging whether a project is successful is not only based on whether a design meets the requirements technically, but also whether the design is reasonable, whether the quality of the product passes the test, whether the cost of the product is properly controlled, and whether the completion time meets the needs. This requires efficient teamwork, detailed demand analysis, accurate solution selection, reasonable project planning, standardized design documents and rigorous project review, and a perfect hardware design process can precisely make these well connected, and it is also The guarantee of a good product design.The above is the hardware design and development process introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have software and hardware function development needs for smart electronic products, you can rest assured to entrust them to us. We have rich experience in customized development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate PCBA quotations. We are a number of chip agents at home and abroad, including MCU, voice IC, Bluetooth IC and modules, wifi modules. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth wifi development, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS solutions, the development of Bluetooth audio, the development of children's toys, and the development of electronic education products.
07-04

2023

Circuit Board Repair Technology

With the rapid development of electronic technology, electronic products are constantly updated. Since there are always various reasons for the failure of electronic products during the production process, there is electronic testing, and testing must be inseparable from testing systems.The test system is composed of multiple circuit boards. Once the circuit board fails, the system cannot work normally. Since each circuit board is expensive, it must be repaired if a fault occurs. The key to repair is analysis, and the process of analysis is the process of finding faults. Each circuit board is composed of one or more functional modules, and each functional module is composed of many components, and there are close connections between these components, so it is an important task to find faulty components. Very difficult thing.If you want to repair the circuit board, you must conduct in-depth research on the circuit board, fully understand the structure of the circuit board and the functions of each module; then there are maintenance methods, and good maintenance methods can make maintenance more effective.1. Maintenance method of circuit boardThe principle of circuit board maintenance method is to look first and then test, first easy and then difficult. The faulty circuit board must first be visually inspected to understand the fault phenomenon through visual inspection. Understanding the fault phenomenon will help to analyze the fault in the next step. The analysis process includes asking, watching, smelling, and measuring. The question is to ask the user about the failure, whether it is caused by improper use or a sudden failure during normal operation, and whether the circuit board has been repaired by others before and which components have been moved. The second thing to look at is to carefully observe the electronic components to see if there are obvious signs of discoloration and burnt, whether there are virtual soldering, reverse soldering, etc., and if necessary, you can use a magnifying glass to observe. Then smell, smell if there is any peculiar smell, once the integrated circuit (especially the high-power device) is burned out, it will smell like rotten eggs. The last thing is to measure is to measure, to analyze and find out the faulty device through measurement, and the measurement is divided into static measurement (that is, measuring the circuit board without power) and power-on measurement. The simplest measurement is to use a multimeter to measure the resistance between the power supply and the ground of the circuit board. Usually, the resistance of the circuit board should not be less than 70Ω. If the resistance is too small (only a few ohms or a dozen ohms), it means that there is Components are broken down or partially broken down.2. Classification of circuit board faultsThe scope of failure includes: local failure and global failure. Partial failure refers to the abnormal operation of one or several functional modules of the system; global failure refers to the operation status of the entire system.Faults are divided into stable faults and unstable faults. Stable refers to failures caused by functional failure of components, short circuits, etc.; unstable refers to: poor contact and poor function of components.3. The working principle of the circuit boardThis paper takes the DPS (measurement device voltage source) board as an example, its main functions are: (1) During the test process, it provides two device power supplies for the device under test according to the applied conditions, one of which has a voltage range of 0~50V, and the other The voltage application range is -50V~0V. (2) Measure the operating current of the device power supply, and the measured value is up to 5A.The device power supply board is composed of DPS1 and DPS2 two-way device power supply. Its main components are: logic control unit, decoding control unit, data converter, voltage and power amplifier, current clamp control unit, current sampling unit, differential amplifier , Relay control unit.The working methods of the DPS board are: pressurization (FV), pressurization flow measurement (FVMI). In the FVMI mode, the driving voltage value is provided to the input driver through the digital-to-analog converter, the output current is sampled by the sampling resistor, converted into a voltage value through the differential amplifier, and then the current value is read back by the analog-to-digital converter. The clamp value can be adjusted according to the load Setting, the clamping current plays the role of current limiting protection.The logical block diagram of the DPS board can be drawn by understanding the structure of the real diagram, as shown in Figure 3. Drawing a logic block diagram can make us understand its working process more clearly, which can provide great help for maintenance.Combined with the working principle and composition of the DPS board introduced earlier (the DPS board is composed of two circuits, one for positive voltage and one for negative voltage), we can see that these components provide positive and negative power supplies. Knowing this kind of information is very helpful for analyzing the circuit board. For example, if the positive voltage cannot be added on the DPS board, but the negative voltage can be added, the positive voltage can be repaired by referring to the negative voltage.When the DPS board fails, it is firstly detected statically. Since the integrated circuit uses direct coupling, there is a certain DC resistance between the other pins of the integrated circuit and the ground. This determined DC resistance is called the internal equivalent resistance of the pin, referred to as R, You can use a multimeter to measure the internal equivalent DC resistance of each pin to judge its quality. If the internal equivalent resistance R of each pin is in line with the standard (we can take a good integrated circuit and measure the internal resistance of each pin with a multimeter If the equivalent resistance R is used as the standard), it means that the integrated circuit is good; otherwise, if the difference from the standard value is too large, it means that there is a fault inside the integrated circuit. One point must be paid attention to when measuring, because there are a large number of non-linear components such as triodes and diodes inside the integrated circuit, it is not possible to judge whether a resistance value is measured in one direction during measurement, so the test leads must be exchanged and measured again to obtain positive and negative values. To the two resistance values, only when the forward and reverse resistance values in R meet the standard can it be concluded that the integrated circuit is intact.In the case where the fault source cannot be found in the static detection, only the DPS board is powered on for on-the-road maintenance. If you want to power on the DPS board, you must extend the DPS board, as long as you extend the DPS board, you can power on and analyze it.In actual maintenance, first measure the voltage of the pin when the power is on. If the voltage is abnormal, you can disconnect the pin connection and measure the voltage of the terminal to judge whether the voltage change is caused by the external components or inside the integrated block circuit; The DC equivalent resistance R between the external circuit and the ground is judged externally. Usually, the DC equivalent resistance (in-circuit resistance) between a pin of an integrated circuit and the grounding pin is measured in the circuit, which is actually the total DC equivalent resistance connected in parallel between R and R. In maintenance, the measurement method of on-circuit voltage and on-circuit resistance is often used in combination. Sometimes the on-circuit voltage and on-circuit resistance deviate from the standard value. It is not necessarily the damage of the integrated circuit, but the damage of the peripheral components that makes the R outside abnormal. , resulting in anomalous on-circuit voltage and on-circuit resistance. At this time, only by measuring the DC equivalent resistance inside the integrated circuit can we judge whether the integrated circuit is good or bad. According to actual maintenance experience, it is not necessary to solder the integrated circuit from the circuit board when measuring the internal DC equivalent resistance of the integrated circuit on the road, as long as the abnormal pin of the voltage or on-circuit resistance is disconnected from the circuit, and the grounding pin is connected to the circuit at the same time. The circuit board is disconnected, and the other pins remain as they are, and the positive and negative resistance values in R between the test pin and the ground pin can be measured to judge whether it is good or bad.4.Draw the circuit diagramNow many manufacturers do not provide the circuit diagram of the circuit board, but if you want to conduct power-on analysis on the circuit board, there is no way to conduct power-on analysis without the circuit diagram, so you have to draw the circuit diagram yourself. To draw a circuit diagram, you need to know the following points:(1) To understand the working conditions of related integrated circuits, first find out the signal input pins and signal output pins of the integrated circuits and the corresponding power pins and ground pins. The power supply pin of the integrated circuit is used to add the DC working voltage output by the rectification and filtering circuit to the internal circuit of the integrated circuit to provide DC power for the internal circuit of the integrated circuit; and the ground pin is used to connect the internal circuit of the integrated circuit The ground wire of the integrated circuit is connected with the ground wire in the circuit of the whole machine, so that the current of the circuit in the integrated circuit forms a loop. Therefore, the power pin and the ground pin are the two most basic and important pins for the normal operation of the integrated circuit.The signal input pin is connected to the circuit output pin of the previous stage, or connected to the signal source of the whole machine circuit, so that if you understand the signal input pin of the integrated circuit, you can move from the subsequent stage to the previous stage. for analysis. In many troubleshooting of circuit boards, for example: no voltage can be applied, no current can be applied, etc., only after the signal output pin of the integrated circuit is determined can the next step of maintenance be carried out, so find out the signal in the integrated circuit. Input and output pins are very important.(2) According to the manual of electronic components, write down the working characteristics of the IC (truth table, working characteristic curve, working voltage, input and output pins), and then simply arrange the positions of the relevant ICs according to the context of the structure diagram . Finally, use a multimeter to measure the relationship between the front and back stages of the IC, so that the connection between them can be simply drawn.5. Circuit board module unit1. Logic control unitThe logic control unit is the main control unit of the circuit board, which is equivalent to the "CPU" of the circuit board and is a programmable logic device. The main function is to control the relay unit, current clamp control unit and measurement unit by logic level.Failure analysis:(1) Since the level from the "logic control unit" is not enough to drive the relay, it must be driven by the drive circuit, so this should be taken into account when the relay does not work properly (logic control failure, drive circuit failure, failure of the relay itself).(2) When the system is powered on, if the "circuit board cannot be found" phenomenon occurs, it can basically be concluded that the logic control unit on the circuit board is faulty.2. Digital-to-analog converter (D/A)The digital-to-analog converter converts the digital signal given by the controller into an actual analog quantity to control external devices. When the DAC is working normally, the output analog voltage is proportional to the input digital quantity, so when the input and output are not proportional, it can be determined that the DAC is invalid.3. Current clampThe main function of the current clamp is to protect the subsequent circuit and the device under test. The current clamp on the DPS board is to protect the voltage and power amplifier of the subsequent stage. Because there are positive and negative power supplies on the DPS board, the clamping current should also have symmetrical positive and negative circuits.It can be seen from Figure 5 that the front stage connected to these two diodes is the clamping part, and the lower-stage operational amplifier circuit connected to this can be found. Use the diode characteristics of the multimeter to measure the relationship between the input and output of the lower-level op-amp circuit, and it can be known that the function of the op-amp circuit is to form a voltage follower. The voltage follower has the function of impedance transformation. The so-called impedance transformation function means that after being amplified by the voltage follower, its output voltage is approximately equal to the electromotive force of the signal source, but its output resistance is very small. This circuit is often used as an input stage, an intermediate stage, and an output stage. class.Fault analysis: When the DPS board is powered on, 5V is added and 5V comes out, but when it is added to more than 5V, it cannot be added (it is always 5V). At this time, the diode used for clamping the input stage of the follower can be removed. , power on again, if the detection returns to normal at this time, it means that the operational amplifier circuit used for clamping is faulty; if the fault persists, conduct reverse analysis to check the previous level, here it should be noted: as long as the current does not enter the closed loop, it can be Open the output pin of the op amp circuit for measurement.4. Current sampling unitCurrent sampling is composed of sampling resistors and relays with corresponding gears. Current measurement (MI) is the output current is sampled by sampling resistors. After sampling, it is converted into voltage through a differential amplifier, and then the current value is read back by an analog-to-digital converter.Fault analysis: The current is divided into many gears by the sampling resistor. If there is an error in a certain gear, first use a multimeter to statically measure the resistance of the sampling resistor. If the measurement is normal, then measure the relay of the corresponding gear. If the measurement is also normal, Then we have to look at the differential amplifier of the subsequent stage. If the measurement is normal, it can be concluded that the logic controller is faulty.6. Precautions for circuit board maintenanceBefore maintenance, anti-static work must be done first, such as wearing anti-static overalls and shoes, and wearing an anti-static wrist strap. The workbench for maintenance should also be treated with anti-static treatment, such as adding an anti-static table.Pay attention to the safety of electricity use, including the maximum bearing capacity of the circuit board when powering on and maintaining the circuit board; when you need to contact strong electricity, you must pay attention to personal safety and take measures to prevent strong electricity.With the continuous development of electronic products, the types and frequency of various equipment failures have also been greatly increased, so the requirements for maintenance personnel are also increasing, especially for those who are new to circuit board maintenance, many people are very confused at the beginning. I don't know where to start, and I don't know what to learn. In fact, if you want to learn circuit board maintenance well, you must have a certain foundation in digital electricity and analog electricity. Theory + method + practice + summary, so that we can deal with all kinds of faults that occur on the circuit board.The above is the maintenance method of the test system circuit board introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have software and hardware function development needs for smart electronic products, you can rest assured to entrust them to us. We have rich experience in customized development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate PCBA quotations. We are a number of chip agents at home and abroad, including MCU, voice IC, Bluetooth IC and modules, wifi modules. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth wifi development, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS solutions, the development of Bluetooth audio, the development of children's toys, and the development of electronic education products.
07-03

2023

High frequency circuit PCB design

For a long time, designers often spend their energy on the verification of programs, electrical principles, parameter redundancy, etc., but seldom spend their energy on the review of PCB design, and it is often because of PCB design defects that lead to a large number of product performance issues. PCB design principles involve many aspects, including various basic principles, anti-interference, electromagnetic compatibility, safety protection, and so on. For these aspects, especially in high-frequency circuits (especially microwave-level high-frequency circuits), the lack of relevant ideas often leads to the failure of the entire R&D project. Many people still stay on the basis of "connecting electrical principles with conductors to play a predetermined role", and even think that "PCB design belongs to the consideration of structure, process and production efficiency". Many engineers also do not fully realize that this link should be the special focus of the entire design work in product design, and mistakenly spend their energy on selecting high-performance components, resulting in a significant increase in cost and little improvement in performance.1. High-speed PCB designIn product engineering, PCB design occupies a very important position, especially in high-frequency electrical design. There are some general rules and these are to be treated as general guidelines. Applying the design principles and skills of high-frequency circuit PCB to the design can greatly improve the success rate of the design.(1) Wiring design principles of high-speed circuit PCB1. Minimize logic fanout, preferably with only one load.2. Avoid using through-holes as much as possible between the output and receiving ends of high-speed signal lines, and avoid crossing pin patterns. Especially the clock signal line needs special attention.3. The signal lines of the upper and lower adjacent layers should be perpendicular to each other to avoid right-angle turns.4. The parallel terminated load resistor should be placed as close as possible to the receiving end.5. In order to ensure the minimum reflection, the length of all open lines (or lines without termination matching) must satisfy the following formula: Lopen——open line length (inches); trise——signal rise time (ns); tpd——line propagation Latency (0.188ns/in - per stripline characteristic).6. When the length of the open line exceeds the value required by the above formula, a series damping resistor should be used, and the series termination resistor should be connected to the pin of the output terminal as much as possible.7. To ensure that the analog and digital circuits are separated, AGND and DGND must be connected together through an inductor or ferrite beads, as close as possible to the A/D converter. 8. Ensure adequate decoupling of the power supply. 9. It is best to use surface mount resistors and capacitors.(2) Bypass and decoupling1. Before selecting a decoupling capacitor, calculate the resonant frequency requirement required to filter high-frequency currents.2. Above the self-resonant frequency, the capacitor will become inductive, thus losing the role of decoupling capacitor. It should be noted that some logic circuits have spectral energy higher than the self-resonant frequency of common decoupling capacitors.3. The resonant frequency of the container itself is called self-resonant frequency. If you want to filter out high frequencies.4. Calculate the required capacitance value based on the RF energy contained in the circuit, the rise time of the switching circuit, and the frequency range of particular interest, rather than guesswork or conventional usage.5. Calculate the resonant frequency of the ground and power planes. The decoupling capacitor constructed on such two planes can achieve maximum benefit.6. For high-speed components and areas with rich RF bandwidth energy, multiple capacitors should be connected in parallel to remove RF energy with a large bandwidth. Also note: when the large capacitor becomes inductive at high frequencies, the small capacitor remains capacitive, and an LC resonant circuit will be formed at a special frequency, resulting in infinite impedance, thus completely losing the bypass function. When this happens, it is more efficient to use a single capacitor.7. Set parallel capacitors on all power input connectors of the circuit board and on the power pins of components whose rise time is faster than 3ns.8. At the diagonal direction of the PCB power input terminal and the wrench, a capacitor with a large enough capacity should be used to ensure the current change when the circuit switches states. The same consideration should be given to the decoupling capacitors of other circuits, the greater the operating current, the greater the required capacitance. To reduce voltage and current pulsation and improve system stability. Therefore, the decoupling capacitor shoulders the dual functions of decoupling and freewheeling.9. If you use too many decoupling capacitors, it will draw a lot of current from the power supply when it is turned on, so a group of large capacitors should be placed at the output of the power supply to provide a large amount of current.(3) Impedance transformation and matching1. In low-frequency circuits, the concept of matching is very important (making the load impedance equal to the conjugate of the excitation source internal resistance). In high-frequency circuits, the matching of signal line terminals is more important:On the one hand, ZL=Zc is required to ensure that there is no standing wave along the line; on the other hand, in order to obtain the maximum power, it is required that the input end of the signal line should be conjugate matched when connected to the excitation source. Therefore, matching has a direct impact on the performance of microwave circuits. It can be seen that if the terminals do not match, reflections and standing waves will occur on the signal line, resulting in a drop in load power (high-power standing waves will also cause ignition at the antinode).Due to the existence of reflected waves, it will have adverse effects on the excitation source, resulting in a decrease in the stability of the operating frequency and output power. However, in practice, the given load impedance is not necessarily the same as the characteristic impedance of the signal line, and the impedance of the signal line and the excitation source is not necessarily conjugate, so it is necessary to understand and apply impedance matching technology.(4) PCB layeringHigh-frequency circuits often have high integration and high wiring density. The use of multi-layer boards is not only necessary for wiring, but also an effective means to reduce interference. Reasonable selection of the number of layers can greatly reduce the size of the printed board. It can make full use of the middle layer to set up shielding, which can be better realized. Nearby grounding can effectively reduce parasitic inductance, can effectively shorten the transmission length of signals, can greatly reduce cross-interference between signals, etc. All of these are beneficial to the reliable operation of high-frequency circuits. There are data showing that four-layer boards of the same material are more expensive than The noise of double-sided panels is 20dB lower, but the higher the number of layers, the more complex the manufacturing process and the higher the cost.(5) Power isolation and ground splitCircuit wiring with different functions or different requirements often requires power isolation and ground wire splitting. For example, analog circuits and digital circuits, weak signal circuits and strong signal circuits, sensitive circuits (PLL, low jitter trigger, etc.)Basic requirements: 1. The power layer or ground layer in different areas should be connected together at the power inlet, usually in a tree structure or finger structure. The ground wire division method of different functional circuits, the division gap and the edge of the board should not be less than 2mm. 2. Power zones and ground zones of different types cannot cross each other. 3. Trench and bridge. Due to the division of the ground plane, the signal transmission return loop between the various functional circuits is often discontinuous. In order to ensure the connection of the signal, power supply and ground, in addition to using transformer isolation (can not transmit DC signals), optocoupler isolation ( Difficult to transmit high frequency), the commonly used bridging method. The "bridge" is actually a gap in the trench, and there is only one. When using this method, it is best to connect both sides of the bridge to chassis ground if it is a multi-point grounding system (as all high-speed designs are).SummarizeIn product engineering, PCB design occupies a very important position, especially in high-frequency electrical design. The same principle design, the same components, PCBs made by different people have different results. There are many things that are feasible in principle but difficult to achieve in engineering, or things that others can achieve but others cannot. Therefore, it is not difficult to make a PCB board, but it is not easy to make a good PCB board. things.The above is the high-frequency circuit PCB design technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have software and hardware function development needs for smart electronic products, you can rest assured to entrust them to us. We have rich experience in customized development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate PCBA quotations. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, Bluetooth IC and module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth wifi development, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
07-02

2023

Through-hole PCB design

DFM design for manufacturability of through-hole PCBThis article introduces some DFM methods related to through-hole packaging. These principles are universal in nature, but not necessarily applicable in every situation. However, for PCB designers and engineers dealing with through-hole technology Believe it or not, it helps.1. PCB typesetting and layoutProper layout at the design stage can avoid many troubles in the manufacturing process.(1) Using a large board can save materials, but due to warpage and weight, it will be difficult to transport during production. It needs to be fixed with special fixtures, so try to avoid using boards larger than 23cm×30cm. It is best to control the size of all the boards within two or three types, which helps to shorten the downtime caused by adjusting the guide rails, repositioning the barcode reader, etc. when the product is replaced, and the number of board sizes is ok Reduce the number of wave soldering profiles.(2) It is a good design method to include different kinds of panels in one board, but only those boards that are finally made into one product and have the same production process requirements can be designed in this way.(3) Some borders should be provided around the board, especially when there are components on the edge of the board, most automatic assembly equipment requires at least 5mm of board edge area.(4) Try to wire on the top surface (component surface) of the board, and the bottom surface (soldering surface) of the circuit board is easily damaged. Do not route wiring close to the edge of the board, because the production process is held by the edge of the board, and the wiring on the edge will be damaged by the claws of the wave soldering equipment or the frame conveyor.(5) For devices with higher pin counts (such as terminal blocks or flat cables), oval pads should be used instead of round. To prevent tin bridges during wave soldering.(6) Make the spacing between the positioning holes and the distance between them and the components as large as possible, and standardize and optimize their size according to the insertion equipment: do not electroplate the positioning holes, because the diameter of the plating holes is difficult to control.(7) Try to make the positioning holes also be used as the mounting holes of the PCB in the final product, which can reduce the drilling process during production.(8) The test circuit pattern can be arranged on the waste edge of the board for process control, and the pattern can be used to monitor the surface insulation resistance, cleanliness, solderability, etc. during the manufacturing process.(9) For larger boards, a path should be left in the center to support the circuit board at the center during wave soldering, to prevent the board from sagging and solder sputtering, and to help the board surface to be welded consistently.(10) The testability of the bed of needles should be considered in the typesetting design. Plane pads (without leads) can be used for better connection with pins during online testing, so that all circuit nodes can be tested.2.The positioning and placement of circuit board components(1) Arrange components in rows and columns according to a grid pattern position, and all axial components should be parallel to each other, so that the axial insertion machine does not need to rotate the PCB during insertion. Unnecessary turning and movement can significantly slow down the inserter.(2) Similar components should be arranged in the same way on the board. For example, make the negative poles of all radial capacitors face the right side of the board, make the missing El marks of all dual in-line packages (DIP) face the same direction, etc., which can speed up the insertion speed and make it easier to find errors.(3) The arrangement direction of dual-in-line packaged devices, connectors and other multi-pin components is perpendicular to the direction of wave soldering, which can reduce the tin bridge between component pins.(4) Make full use of silk screen to mark the board surface, for example, draw a frame for barcode, print an arrow to indicate the direction of the board through wave soldering, and use a dotted line to trace the outline of the bottom surface components (so that the board only needs to be silk screened once) )etc.(5) Draw the component reference designation (CRD) and polarity indication, and it is still visible after the component is inserted, which is very helpful in inspection and troubleshooting, and is also a good maintenance job.(6) The distance between the components and the edge of the board should be at least 15mm (preferably 3mm), which will make the circuit board easier to transfer and wave solder, and will cause less damage to peripheral components.(7) When the distance between the component and the board needs to exceed 2mm (such as light-emitting diodes, high-power resistors, etc.), gaskets should be added below it. Without spacers, these elements would be "squashed" during transport and would be susceptible to vibration and shock in use.(8) Avoid placing components on both sides of the PCB, because this will greatly increase the labor and time of assembly. If the component must be placed on the bottom surface. It should be physically close as possible so that the masking and stripping of the solder mask tape can be completed at one time.(9) Try to distribute the components evenly on the PCB to reduce warpage and help to distribute heat evenly during wave soldering.3. Circuit board machine insertion(1) The pads of all board components should be standard and industry standard spacing should be used.(2) The selected components should be suitable for machine insertion. Keep in mind the conditions and specifications of the equipment in your own factory, and consider the packaging form of the components in advance so that they can better cooperate with the machine. Packaging can be a bigger issue for odd-shaped components.(3) If possible, the axial type of the radial element should be used as much as possible, because the insertion cost of the axial element is relatively low. If the space is very precious, the radial element can also be preferred.(4) If there are only a small number of axial elements on the board, all of them should be converted to radial type, and vice versa, so that an insertion process can be completely saved.(5) When laying out the board surface, the direction of pin bending and the reach of the components of the automatic insertion machine should be considered from the perspective of the minimum electrical spacing, and at the same time, it should be ensured that the direction of pin bending will not cause tin bridges.4. Wires and connectors(1) Do not connect wires or cables directly to the PCB, but use connectors. If the wire must be soldered directly to the board, the end of the wire should be terminated with a wire to a terminal on the board. The wires coming out of the circuit board should be concentrated in a certain area of the board so that they can be nested together to avoid affecting other components.(2) Use wires of different colors to prevent errors during assembly. Each company can adopt its own set of color schemes, for example, the high position of all product data lines is represented by blue, while the low position is represented by yellow, etc.(3) The connector should have larger pads to provide a better mechanical connection, and the leads of high-pin-count connectors should have chamfers for easier insertion.(4) Avoid using dual in-line package sockets. In addition to prolonging assembly time, this additional mechanical connection reduces long-term reliability, and sockets should only be used when DIP field replacement is required for maintenance reasons. The quality of DlP has made great progress nowadays, and it does not need to be replaced frequently.(5) Marks to identify the direction should be engraved on the board to prevent mistakes when installing the connector. The solder joints of the connectors are places where mechanical stress is more concentrated, so it is recommended to use some gripping tools, such as keys and snaps.5.The whole system(1) Components should be selected before designing the printed circuit board, which can achieve the best layout and help implement the DFM principles described in this article.(2) Avoid using parts that require machine pressure, such as wire pins, rivets, etc. In addition to being slow to install, these parts may also damage the circuit board, and they are also poor in maintainability. (3) Use the following method to minimize the types of components used on the board: replace a single resistor with a row resistor: replace two three-pin connectors with a six-pin connector. The values of the two components are very similar, but If the tolerances are different, use the one with the lower tolerance for both locations: use the same screws to hold the various heatsinks on the board. (4) It is best designed as a universal board that can be configured on site. Such as installing a switch to change a board for domestic use to an export model, or using a jumper to change one model to another.6. Conventional requirements for PCB board design(1) When conformal coating is applied to circuit boards, the parts that do not require coating should be marked on the drawing during engineering design. The influence of the coating on the line-to-line capacitance should be considered in the design.(2) For through holes, in order to ensure the best welding effect, the gap between the pin and the aperture should be between 0.25mm and 0.7Omm. A larger aperture is beneficial for machine insertion, but a smaller aperture is required to obtain a good capillary effect, so a balance needs to be struck between the two.(3) Components that have been pretreated according to industry standards should be selected. Component preparation is one of the least efficient parts of the production process, and in addition to adding an extra step (with a corresponding risk of electrostatic damage and longer lead times), it also increases the chance for error.(4) Specifications should be determined for most of the manual plug-in components purchased, so that the length of the lead wires on the soldering surface of the circuit board does not exceed 1.5mm. This reduces component preparation and lead trimming effort, and the board passes wave soldering equipment better. (5) Avoid using snap fits for smaller mounts and radiators, as this is slow and requires tools. Sleeves, plastic quick-connect rivets, double-sided tape, or mechanical connections using solder joints should be used whenever possible.SummarizeFor manufacturers of board assemblies using through-hole technology, the DFM is an extremely useful tool that saves a lot of money and hassle. The benefits of using DFM methods to reduce engineering changes and make future design compromises are very immediate.The above are the details of DFM design for manufacturability of through-hole PCB introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have software and hardware function development needs for smart electronic products, you can rest assured to entrust them to us. We have rich experience in customized development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate PCBA quotations. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, Bluetooth IC and module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth wifi development, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.
07-01

2023

PCB board anti-ESD design

Anti-ESD design method of PCB board in electronic equipmentIn the design process of electronic products, designers usually start to consider the problem of anti-static discharge (ESD) when the product enters the production process. In order to make electronic equipment pass the anti-static discharge test without destroying the original design, the final solution usually uses expensive components, manual assembly during the manufacturing process, and even a redesign of the PCB board. progress is bound to be affected. Therefore, in the process of designing the PCB board of electronic products, it is necessary to consider the problem of optimizing ESD protection.1. The impact of ESD on electronic equipmentAnti-electrostatic discharge (ESD) design rules must be followed in the design of electronic products, because most electronic devices are in an environment full of ESD for 99% of their lifespan, especially in the current portable products. Low-power logic chips, most of them are designed and manufactured based on CMOS technology, due to the metal oxide semiconductor (MOS) dielectric breakdown and bipolar reverse junction current limitation, these IC chips are very sensitive to ESD. Additionally, most I/O ports (especially USB ports) are hot-swappable systems that are highly susceptible to ESD from the user or from air discharge. ESD can come from the human body, furniture, or even inside the device itself. Although it is rare for electronic equipment to be completely damaged by ESD, ESD interference is very common. ESD interference may cause device lockup, reset, data loss or reduced reliability, and may even cause data bit ghosting, product damage, and even damage to electronic equipment. "Hard fault" or component failure. The result may be: in the cold and dry winter, electronic equipment often fails, but it is normal when repaired, which will inevitably affect the confidence of users in electronic equipment and its manufacturers. It can be seen that it is very necessary to consider ESD protection during the design of electronic products, especially the design of its PCB board.2. The mechanism of ESD generationWhat is ESD? How does ESD enter electronic equipment? ESD has the potential to occur when a charged conductor is in close proximity to another conductor. First, a strong electric field will be established between the two conductors, resulting in field-induced breakdown. An arc occurs when the voltage between two conductors exceeds the breakdown voltage of the air and insulating medium between them. In the time from 0.7ns to 10ns, the arc current will reach dozens of amperes, and sometimes even exceed 100A. The arc will continue until the two conductors touch short or the current is too low to sustain the arc. The generation of ESD depends on the initial voltage, resistance, inductance and parasitic capacitance of the object, for example: the human body, charged devices and machines may generate arcs, hands or metal objects may generate spike arcs, furniture may generate the same polarity or polarity changes Multiple arcs. ESD can enter electronic equipment through the following five coupling paths:(1) The initial electric field can capacitively couple to the network with a large surface area, and generate a high voltage of up to 4000V/m at a distance of 100mm from the ESD arc.(2) The charge/current injected by the arc can cause the following damage and failure: ① Penetrate the thin insulating layer inside the component and damage the gate of MOSFET and CMOS components (common). ②Flip-flop lockup in CMOS devices (common). ③Short-circuit reverse-biased PN junction (common). ④ Short circuit forward biased PN junction (rare). ⑤ Melt the welding wire or aluminum wire inside the active device (rare).(3) The current will cause voltage pulses (V=L×dI/dt) to be generated on the conductors. These conductors may be power supply, ground or signal lines. These voltage pulses will enter every component connected to these networks (common).(4) The arc will generate a strong magnetic field with a frequency range of 1 MHz to 500 MHz, and inductively couple to each adjacent wiring loop, generating a current up to 1 5A/m at a distance of 1 00 mm from the ESD arc.(5) The electromagnetic field radiated by the arc will be coupled to long signal lines, which act as receiving antennas (rare). It can be seen that the ESD frequency range is wide, and it is possible to find the weak point of the device through various coupling paths.In order to prevent ESD interference and damage, the anti-ESD ability of the equipment should be comprehensively considered from the following three aspects:Selection of components: such as considering the ESD capacity of the chip, using a transient voltage suppressor (TVS) diode array, etc.; PCB layout design: such as increasing the grounding area as much as possible, shortening the PCB trace, etc.;Mechanical design: For example, shielding measures such as plastic chassis and air space are used to effectively solve ESD problems.Among them, PCB layout design is one of the most critical elements to optimize ESD protection. Reasonable PCB design can reduce unnecessary costs caused by fault inspection and rework.3. Anti-ESD design method of PCB boardBy analyzing the mechanism of ESD and its hazards, designers can consider optimizing the PCB design scheme for ESD protection from the following aspects:3.1 Reduce circuit loop areaCurrent is induced into closed circuit loops that also have varying magnetic flux. The area of the loop is proportional to the magnitude of the current. The larger the area of the loop, the greater the magnetic flux contained, and thus the greater the current induced in the circuit. Therefore, it is necessary to reduce the loop area as much as possible during design.Figure 1 shows one of the most common circuit loops, formed by power and ground. Where possible, a multilayer PCB design with power and ground planes can be used. The multi-layer circuit board not only minimizes the loop area between the power supply and the ground, but also the ground plane and the power plane, as well as the closely arranged signal line-ground spacing can reduce the common impedance (common impedance) and inductive coupling, and also reduce the The high-frequency EM I electromagnetic field generated by the ESD pulse is reduced.If the use of multi-layer circuit boards is limited by conditions, then the grid structure shown in Figure 2 must be used for power lines and ground lines. The grid size of this grid structure is less than or equal to 60mm, and if possible, the grid size is preferably less than 1 3 mm (0. 5in.). Between vertical and horizontal lines or filled areas, connect as many as possible. Also, keeping the power and ground traces as close as possible can also reduce the loop area.Another way to reduce loop area and induced current is to reduce parallel paths between interconnecting devices.3.2 Shorten the length of the circuit connectionA long signal line can be used as an antenna for receiving ESD pulse energy. In the design, try to use a signal line less than 30cm to reduce the efficiency of the signal line as an antenna for receiving ESD electromagnetic fields. And try to put the interconnected devices in adjacent positions, so that the length of the interconnected printed lines is as short as possible.When it is necessary to use a signal connection line longer than 30cm, a protection line can be used, as shown in Figure 5. The ground layer should be placed near the signal line, and the distance between the signal line and the ground line layer (or protection line) should be less than 1 3 mm (0. 5in.).Another way is to cross the signal line or power line longer than 30cm and its grounding line. The crossed lines must be arranged at regular intervals from top to bottom or from left to right.3.3 Protect all external connections with TVS diodesAdding a TVS device on the power line can help solve the problem of ESD from the power port connected to the power supply. TVS connected to Vcc and ground can prevent ESD interference from the power supply, but the parasitic inductance in the protection circuit should be considered.During an ESD event, the parasitic inductance in the TVS diode path can generate severe voltage overshoot. Although a TVS diode is used, the total voltage that the protection circuit can withstand is the sum of the clamp voltage of the TVS diode and the voltage generated by the parasitic inductance: V T=V C+VL, due to the induced voltage VL=L×dI/dt at both ends of the inductive load , the excessively high overshoot voltage may still exceed the damage voltage threshold of the protected IC. An ESD transient induced current can reach its peak value in less than 1 ns (according to the IEC 61 000-4-2 standard), for example: the lead inductance is 20nH per inch, and the line length is a quarter of an inch. The impulse voltage will be a pulse of 50V/1 0A. Therefore, the shunt path should be designed as short as possible in order to reduce the effect of parasitic inductance. Ground loops must be considered when designing all inductive paths, namely: the path between the TVS and the signal line to be protected, and the path from the connector to the TVS device. In order to reduce the parasitic inductance of the ground plane, the distance between the ground of the TVS diode and the ground point of the protected circuit should be as short as possible.3.4 Reduce ground charge injectionSensitive circuits may be damaged during direct discharge of ESD to the ground plane. Therefore, one or more high-frequency bypass capacitors must be used along with the TVS diodes to protect the power supply from ESD disturbances, as shown in Figure 7. These capacitors are connected between power and ground for vulnerable components. The bypass capacitor can reduce the injection of ground charge, so that the voltage difference between the power supply and the ground port is clamped. The TVS shunts the sense current and maintains the potential difference of the TVS clamping voltage. In addition, TVS and capacitors should be placed as close as possible to the protected IC. In order to reduce the effect of parasitic inductance, ensure that the path from TVS to ground and the length of capacitor pins are the shortest. The connector must be mounted to the copper-platinum plane on the PCB. Ideally, the copper-platinum layer must be isolated from the ground plane of the PCB and connected to the pad by a short wire.
06-29

2023

Bluetooth speaker product development

Bluetooth speaker product development refers to the process of designing and manufacturing Bluetooth speaker devices. Bluetooth speaker is an audio device with Bluetooth wireless connection function, which can receive and play audio content from various audio sources (such as smartphones, tablets, computers, etc.) through Bluetooth technology. Here are the main technical aspects involved:Bluetooth technology: Bluetooth speakers need to support Bluetooth wireless connections, enabling them to establish connections with other Bluetooth devices (such as audio source devices) and transmit audio data. Bluetooth technology involves the Bluetooth protocol stack, Bluetooth profiles, etc. to ensure compatibility and communication capabilities between speakers and other devices.Audio processing and decoding technology: Bluetooth speakers need to be able to receive, decode, and process audio data in different formats to provide high-quality audio output. This may involve audio codecs, digital signal processing (DSP), audio amplifiers and other technologies to ensure accurate restoration and amplification of audio signals.Battery management and power optimization: Bluetooth speakers often require built-in batteries for mobile use. Therefore, battery management and power consumption optimization are important technical considerations. This includes designing efficient power management circuits, adopting low-power components, and optimizing power control algorithms to extend battery life and provide long usage times.Acoustic Design and Audio Drivers: The acoustic design of a Bluetooth speaker is an important aspect in ensuring good sound quality and volume performance. This involves choosing the right loudspeaker drivers, designing proper speaker cabinets and acoustic isolation to achieve superior sound quality and audio performance.User interface and control: Bluetooth speakers usually have user interface and control functions to facilitate users to perform operations such as speaker settings, volume adjustment, and audio source switching. This may include buttons, knobs, touch panels, remote controls, apps, and many other forms of user interface.Wireless connection stability and distance coverage: Bluetooth speakers need to provide reliable wireless connection stability and achieve good signal coverage within a certain distance. This requires consideration of technical means such as antenna design, signal interference elimination, and signal attenuation compensation.Connection stability and multi-device connection: Bluetooth speakers usually support multiple devices connected at the same time, such as connecting multiple smartphones or other audio source devices. Therefore, technologies that ensure connection stability, multi-device switching, and management are required during development.Waterproof and dustproof design: Bluetooth speakers often need to have waterproof and dustproof functions to adapt to outdoor and various environmental conditions. This requires techniques such as proper seal design, waterproof coating, material selection, etc.Device interoperability and compatibility: When developing a Bluetooth speaker, consider interoperability and compatibility with other devices to ensure that it can pair and communicate with various makes and models of audio source devices.Remote control and smart functions: Some advanced Bluetooth speaker products may support remote control and smart functions, such as voice assistant integration, smart home integration, speaker cloud services, etc. This involves technologies such as integration with cloud platforms, smart home protocols, and related application development.Manufacturing and production technology: The development of Bluetooth speakers also involves manufacturing and production technology, including PCB design, assembly process, quality control, etc., to ensure the manufacturability and consistency of products.It should be noted that the specific Bluetooth speaker development process and the technologies involved may vary depending on the product type, functional requirements, and manufacturer. Therefore, in actual development, technology selection and customized development may be required according to specific requirements.
06-28

2023

Bluetooth headset product development

Bluetooth headset product development refers to the process of designing and manufacturing Bluetooth wireless headset devices. A Bluetooth headset is a headset device that is wirelessly connected to an audio source device through Bluetooth technology and provides audio playback and call functions. Here are the main technical aspects involved:Bluetooth technology: Bluetooth headsets need to support Bluetooth wireless connections to establish connections with audio source devices (such as smartphones, tablets, etc.) and transmit audio data. Bluetooth technology involves the Bluetooth protocol stack, Bluetooth profiles, etc. to ensure compatibility and communication capabilities between the headset and other devices.Audio processing and decoding technology: Bluetooth headsets need to be able to receive, decode, and process audio data from audio source devices to provide high-quality audio playback and call functions. This may involve audio codecs, digital signal processing (DSP), noise reduction techniques, etc. to achieve clear audio.Battery management and power optimization: Bluetooth headsets often require built-in batteries for mobile use. Therefore, battery management and power consumption optimization are important technical considerations. This includes designing efficient power management circuits, adopting low-power components, and optimizing power control algorithms to extend battery life and provide long usage times.Wireless connection stability and distance coverage: Bluetooth headsets need to provide reliable wireless connection stability and achieve good signal coverage within a certain distance. This requires consideration of technical means such as antenna design, signal interference elimination, and signal attenuation compensation.User interface and control: Bluetooth headsets usually have a user interface and control functions to facilitate operations such as volume adjustment, song switching, and answering/rejecting calls. This may include buttons, touch controls, voice controls, and many other forms of user interface.Waterproof and sweatproof design: Since Bluetooth headsets are often used in sports and outdoor activities, waterproof and sweatproof design has become an important technical requirement. This may involve waterproof coating, waterproof seal design, material selection, etc. to provide reliability and durability of the headset in wet environments.Noise control and noise reduction technology: Bluetooth headsets often need to provide good noise control and noise reduction functions to reduce the impact of environmental noise on audio quality and call clarity. This may involve active noise reduction technology, ambient sound transfer function, etc., to provide a better audio experience.Device interoperability and compatibility: When developing a Bluetooth headset, consider interoperability and compatibility with other devices to ensure pairing and communication with various makes and models of audio source devices.Audio coding and transmission protocols: Bluetooth headsets need to support appropriate audio coding and transmission protocols, such as SBC (Subband Coding), AAC (Advanced Audio Coding), etc., to achieve high-quality audio transmission and compatibility.Headset Design and Ergonomics: Bluetooth headsets need to be designed with comfort, stability, and ergonomics in mind. This includes the shape and material selection of the eartips or earmuffs, the weight balance of the headphones, the adjustable over-the-head structure, etc. to provide a comfortable wearing experience.Charging technology and wireless charging: Bluetooth headphones are usually charged through a charging case or charging cable. During product development, appropriate charging technology and interface design, as well as possible wireless charging capabilities, need to be considered.Reliability and quality control: Bluetooth headsets need to withstand the test of daily use and portability, so reliability and quality control are important technical considerations. This includes designing durable housing materials, conducting reliability testing and quality control processes, etc. to ensure product stability and reliability.It should be noted that the specific Bluetooth headset development process and the technologies involved may vary depending on the product type, functional requirements, and manufacturer. Therefore, in actual development, technology selection and customized development may be required according to specific requirements.

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