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UCC21710QDWEVM-025: RDY fault output

YoonJin Kim
Prodigy 120 points
Part Number: UCC21710QDWEVM-025
Other Parts Discussed in Thread: UCC21710

Hello.

I apply power input on VCC1(TP5) 5V and GND(J2:11) 0V, 5-0V PWM signal on IN+ and short TP11 with OC pin. 

At one point during the evaluation, RDY led was turned off and there became no output.

I measured the value on pin of Gate Driver IC UCC21710 directly using Digital multimeter and the value was

RDY=38mV, FLT bar=1.8V, RST bar/EN=4V, VDD=16V, COM=0V, VEE=-5V

I think all the value is okay except RDY pin.

There seems to be no output after RDY output drops. I want to know if there is something wrong with the internal logic in RDY and if there is a solution. 

Thank you.

  • 0
    TI__Expert 5040 points

    Hi YoonJin, 

    Just to understand the problem better - during the operation, the RDY pin dropped to low (38mV) while nFLT and EN/nRST remained high, correct? 

    RDY would drop if there's an UVLO issue on either VCC or VDD. Can you verify that the voltage between VCC-GND and VDD-COM is stable and above the UVLO threshold on the gate driver pins again? Using the oscilloscope to measure might be the better choice since the multimeter does not allow you to see the noise on those pins. If you can send me a screenshot that would be great. 

    Also a couple of question from us - did the RDY and output recover after some time, or did it remain low? And how reproducible was the issue? 

    Looking forward to hearing back! 

    Thanks, 

    Vivian