We are testing a DC-DC converter and the gate driver is Si8233BD. A 50kHz, 3.3V PWM is generated from the TI28377S launchpad (DSP) and is given to the driver IC (VIA, VIB). We are getting the VOA output pulses, but the VOB is always clamped to high. Please find the attached schematics. Could you please help us to resolve the issue.
It would be useful to see input and output waveforms to help diagnose this problem.
I also note that you are using a driver with an 8V UVLO (output side) while your SiC device gate charge plateau is at 9.5V. I'm not sure if this would make the difference given that you imply that VOA and VOB are both high enough (and long enough?) to turn the devices on.
If you are getting sag in your 18V supply during switching, this might create an issue. If you don't have enough bypass cap on that supply, that could also create a problem.
If you decide to provide waveforms, please also provide a waveform for the 18V supply.