关键词: 数字隔离器, 失效分析, 带隙基准, 工艺偏差

Abstract: When a certain aerospace electronic system uses a certain type of digital isolator circuit, the signal transmission is abnormal when it is powered on.The fault-analysis-tree is established for the abnormal points, and the failure points of the coding chip, transformer chip, low dropout regulator (LDO) and decoding chip in the failure circuit are located. By band-gap reference(BGR) of internal circuit, pin test of error-amplifier output, ATE power on slope test, power supplyon simulation and other means, it is found that the fault circuit has manufacturing process deviation, which leads to the BGR cannot be established correctly when the power on slope is low, thus leading to abnormal LDO output. Such failures can be effectively eliminated by tightening ATE test program. The board level test verification is carried out to solve this problem, which provides a basis for the subsequent circuit revision and similar circuit design.

Key words: digital isolators, failure analysis, band-gap reference, process variation