Immunity test and failure analysis of tunneling magnetoresistance current sensor

Tunneling magnetoresistance (TMR) current sensor chips, known for their high sensitivity and wide frequency band characteristics, represent an important development direction for current monitoring in power systems. However, their interference resistance and failure mechanisms in complex electromagnetic environments still require further in-depth research. This paper constructs an integrated circuit-level transient pulse immunity test platform based on the IEC 62215-3, IEC 61000-4-4, and IEC $61000-4-5$ standards. It conducts a comparison test on the immunity to electrical fast transient (EFT) and surge pulses for two TMR current sensor chips with different structures, and analyzes the electromagnetic sensitive modules and failure mechanisms of the chips. The results show that the TMR magnetosensitive units exhibit high immunity in both EFT and surge tests. However, the chips with integrated signal conditioning modules fail at lower voltage levels. Optical microscopy and scanning electron microscopy (SEM) observations of the failed chips reveal that the primary cause of failure is the melting of the metal plating layer in the signal conditioning module, which is due to cumulative Joule heating or instantaneous overcurrent.