Study On In-circuit Test System Of The Typical Analog Components On Electronic Functional Module

Electronic function module is printed circuit function board with various electronic components, which is an important part of the electronic products and electromechanical equipment, its quality directly affects the working status of the whole products and equipment. And analog components are the indispensable element of electronic function module, it is especially important to test them. Many systems appear on the market in recent years, which are used to diagnose electronic function module whether there exists fault in the process of production, but they are mostly produced by Europe and America, it is hard to bear the expensive price for medium and small-sized electronic enterprises in our country. In order to improve the market competitiveness of these enterprises, it is great significance to research and develop in-circuit test system of electronic function module with cheap price and convenient use.Firstly, the basic principle and relevant test methods of in-circuit test technology for analog components are discussed in this article, on this basis the design ideas of virtual instrument and USB2.0 communication technology are adopted, and the scheme of in-circuit test system is determined for the typical analog components on the electronic function module. Second, the hardware circuits designs of each part belong to system are expounded in detail, including four sections consist of the key control module, in-circuit test unit, relay array and needle-bed. The difficulty of which is the design of in-circuit test unit, three-wire test method and six-wire test method are used to solve effectively the key problem that isolates measured components from others on measured electronic function module in the paper. In addition, the visual interface of application program is designed using VC++6.0 development environment in software, which can communicate with hardware circuits by USB, and control hardware circuit to complete test work. Finally, in-circuit test system is built that combining hardware and software based on the above the design, and the test methods of the system are described in detail by an example to verify the operability and practicability of system.The practical test results show that in-circuit test system based on virtual instrument technology can directly measure parameters of the components on electronic function module without taking down them, which has good universality, simple test process and practical value.