Hello,

I am working to develop a high-side switch in a high-voltage (600V) circuit used to charge a capacitor. The purpose of the switch is to isolate a DC power supply from a controlled plasma breakdown, which drains the charge in the capacitor. The switch works great when during a simple charge/discharge of the capacitor through a resistor. The problem comes when I introduce the plasma breakdown, my high-side gate-driver IC (Fairchild FAN7392) sees a large negative voltage (~ -100 V). The chip burns and actually starts smoking.

I have tried to remedy this by placing a diode and a resistor directly after the Vs, however the chip is still going bust.

Any suggestions or help? Could it be that the diode I am using doesn't clamp fast enough?

Thanks.