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UCC21710-Q1: UCC21710-Q1 VDD short to COM issue

jimmy zhang77361
Intellectual 315 points
Part Number: UCC21710-Q1

We use UCC21710-Q1 to drive a SIC-MOSFET and use a isolation power supply to power UCC21710-Q1.. But when we power-up the board, the circuit does not work. Later it was found that the resistance between "VDD" pin and "COM" pin is very small, less than 1Ohm.. What is the root-cause for this? Is this due to power supply "VDD to COM"  is to big and damage the chip?

  • 0
    TI__Genius 10652 points

    Hi Jimmy, 

    VOltages exceeding Abs. Max. on VDD could damage the IC in this way, but its hard to tell what happened without knowing more. I would suggest to dig in more and see. 

    Generally, the voltage on VDD would actually need to be high for a prolonged time to cause damage. 

    1) What other external components were damaged? Was SiC Fet damaged?

    2) Was the inverter running? Or damaged immediately 

    3) Is there a potential for loss of regulation of VDD on power-on?

    4) Are any other pins shorted/open circuit on the gate driver?

    We also need to know if this issue is reproducible. If this issue is isolated to just one board and cannot be reproduced, it is very difficult to identify a root cause. 

    I would suggest to replace all damaged components on that board and "stress" that phase/driver circuit of the PCB, especially at Power-up, or run it many times and probe VDD-COM and COM-VEE and any other critical signals you might identify are suspect.   I would also suggest to see if the issue can be reproduced on other boards. 

    Please let me know an updates. 

    Best

    DImitri