I designed a constant current buck DC-DC super-cap charger with the NCP3420 as a dual MOSFET driver. The current is hysteresis controlled and the disable and PWM lines are pulled low on power-up.
The circuit is working, but sometimes the driver fails during power-up with the controls pulled low, shorting out the 12V supply. What would cause this?
Link to NCP3420 Datasheet: https://www.onsemi.com/pub/Collateral/NCP3420-D.PDF
X1-1 and X1-2 are 12V inputs from my lab supply
X2-1 and X2-2 are connected to a super-capacitor
The 100n cap is a ceramic 50V
The input is also decoupled by 4 parallel 100n ceramics + 6800µ electrolytic
The diode is a schottky rated 80V, 500mA