Abstract: Transient overvoltage at the output pin of a high-side driver IC in the field of industrial control and automotive electronics is caused by back-EMF from inductive load turn-off and conducted surges from the power rail, and it is susceptible to damage. The on-chip protection structures have a small amount of energy absorption capacity, and a full off-chip solution has not been put forward yet. Therefore, we will study the generation mechanism and conduction path of surge voltages in high-side isolated gate driver circuits. A composite off-chip suppression circuit has been proposed; it is made up of a TVS diode, a P-channel clamping MOSFET and an RC snubber network, and both the full-parameter design method for reverse freewheeling and forward overvoltage situations have been developed. The two verification methods are LTSPICE simulation and a 12V experimental platform; it can be confirmed through these that the proposed scheme has reduced the peak of the inductive load turn-off surge from 48V to 15.3V and has a protection response time of less than 80ns. Set the simulation clamp to -2.3V, and then the driver IC will be able to work normally for all five pulse categories of ISO 7637-2. No extra control logic is needed for the circuit; it is small and simple