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UCC21750: IC failing issue

jega arun raja kandaswmay
Prodigy 10 points
Part Number: UCC21750

Tool/software:

iam using  UCC21750DWR for IGBT module switching at 5khz .it is fine but sometimes the IC's are failing also power for this UCC21750dwr is UCC14241QDWNRQ1 this also failing frequently also this ic is heating. can any one please helpme with this  this is UCC21750DWR UCC14241QDWNRQ1this is 

  • 0
    TI__Expert 6220 points

    Hello, 

    Could you elaborate what you mean by failing? Is the gate driver IC damaged and no longer produces output, or there are some other errors (nFLT reporting, RDY reporting, etc.)? 

    Looking at the schematic, I don't see a high voltage diode on the DESAT path. Can you confirm it's indeed present? Without the high voltage diode, DESAT pin voltage can go over the absolute maximum very easily. 

    If UCC21750 is heated up and damaged while UCC14241 is also damaged, there also might be a power supply issue. I recommend checking VCC, VDD, VEE to make sure it's within the device's operating regions. 

    Thanks, 

    Vivian

  • 0 in reply to Vivian Qi
    Prodigy 10 points

    In some gate driver ic's the FLT, RDY Led is glowing for this i have checked the power supply ic output voltage it looks fine. after changing the gate driver ic then it is fine. For DESAT the diodes all are in another Board from that i am taking the I/p for that.

    ICS damaged means, some ic's that RDY, FLT led is glowing. some ic's after replacing then the pwm output is fine 

    IGBT part no. FF450R12KT4 

    Both power supply ic and gate driver ic are failing (no longer produces output)

  • 0 in reply to jega arun raja kandaswmay
    TI__Expert 6220 points

    Hi, 

    If after replacing the gate driver IC the issue goes away then I suspect it's a gate driver damage issue; nFLT/RDY might be shorted to COM. You can confirm by capturing the waveforms of VCC, VDD, DESAT, RDY, nFLT. If VCC/VDD is stable and above UVLO while RDY is pulled low, then RDY pin might be damaged inside; if DESAT is constantly low while nFLT is pulled low, then nFLT might be damaged inside. You can also check the impedance between RDY and GND and between nFLT and COM of the bad unit and compare the values to a good unit. 

    If both the power supply IC and the gate driver IC are failing, I suspect the power supply IC is not properly configured and might cause EOS (electrical overstress) to the gate driver IC. Please reach out to the power supply IC team for a schematic review. 

    Thanks, 

    Vivian