Hi,
UCC21710 does not seem to drive the gate to low unless provided with negative voltage at input in simulation.
Drive voltage still high at 0 V input.
It works fine if I apply negative voltage.
This is my simulation file: MOSFETDriverM.TSC. Is there something wrong with the simulation or does UCC21710-Q1 actually require negative voltage to pull gate to low?
Regards,
Ayman
Ayman,
UCC21710-Q1 does NOT require negative voltage, you are correct. That is bizarre issue and most likely some nuance with the model and the schematic you have.
A few points on the design i noticed
* please check your DESAT circuit. I am not sure why its tied to OUTH
* FLT_N pin should be pulled up to VCC. You should monitor this because in your schematic you are having fault each cycle. Thats why drive is going low at all.
* When running your schematic even with negative voltage on input, there is a fault condition and in fact it would only work for one cycle. The fault condition must be corrected.
* CLMPI shouldn't have a resistor on it, tie it directly to gate. ( this would matter in final PCB)
Please check the following simulation i have run based on yours.
I first seperated the grounds GND and COM by voltage source. Then ran with 0-6V ( no negative on input) successfully.
I then removed the voltage source and tied the jumper directly to gnd. Sim ran OK.
Then i tied the low voltage grounds back to HV ground by ground symbol. Sim ran OK. Surprisingly this was not the case initially.
I would suggest first , simply seperate LV and HV ground by VDC source, or break them somehow, and then try connecting back directly like i did.
Try these steps and let me know if you still having issues. If you still have issues probe RDY/FLT as well so we can see what of fault/uvlo condition being produced by the model.
Best
Dimitri
Dimitri,
Thank you for your reply. I tried following the steps you mentioned but it didn't work for me. I still seem to get a fault each cycle.
Regards,
Ayman
