Microcontroller Unit ESD-Induced Soft Failure Study

Soft failures caused by system-level electrostatic discharges(ESD) can lead to functional abnormalities of chips in practical applications and have become one of the important forms of chip failures. However, there has always been a lack of a test method that can measure the power supply noise directly related to soft failures. This article presents the testing and analysis of power supply noise on actual microcontroller unit (MCU) products. Ground-Signal-Ground(GSG) probes are directly used to test the actual waveform of the power supply on the operating MCU when system-level ESD pulses are injected. The tested power supply noise waveform is utilized to analyze the soft-failure problems of the MCU chip and guide the design of the on-chip Low Dropout Regulator (LDO). By improving the design of the on-chip LDO, the system-level ESD soft-failure level of this MCU has been tripled.