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UCC21750QDWEVM-025: UCC21750DW

Tohfa
Prodigy 20 points
Part Number: UCC21750QDWEVM-025

Tool/software:

I have designed a gate driver board using UCC21750DW for a 2kV device. But when the device sees 1.5kV(1.12kV nominal voltage+30% overshoot), it trips. The fault pin became low. It happed constantly for one switch, and other switches were fine. We designed the gated driver for an Activer Front End circuit. I am attaching the circuit four your reference. 

We were suspecting that it it the desat pin which is activeting this issue. But we disabled desat pin using a 0ohm jumper resistor. Is this device is correct for the 2kV SiC? Can this truly handle 1.2`1.5kV rms voltage? Please let me know your thoughts on this problem

  • 0
    TI__Expert 8065 points

    Hi Tohfa,

    Thanks for sharing your schematic and explaining the problem statement. The schematic looks good -I don't see any issues.

    FLT will go low only during DESAT event. (when DESAT voltage > threshold voltage).

    • Is it possible to capture the following for us to understand the system behavior?
      • INP, FLT, GATE, VCE voltages during the FLT condition
      • Please use high BW probe+ scope so that 500Mhz or higher BW used to capture the signals.
    • is the failure observed only on specific system voltage onwards, is there any current dependency to it?

    Thanks

    Sasi

  • 0 in reply to Sasikala Thangam
    Prodigy 20 points

    Here are some results. We always saw the upper switch for leg1 to trip after reaching 1.5kV exactly. We have connected FLT to LED and it turns off after that.

  • 0 in reply to Tohfa
    TI__Expert 8065 points

    Hi Tohfa,

    Thanks for sharing the waveforms. What is input source DC voltage and current? Is the left one with no FLT and right one with FLT?

    can you please share all the requested signals and also zoomed in waveform, we want to see the timing between INP, FLT, OUT and also noise in the VCE.

    Thanks

    Sasi

  • 0 in reply to Sasikala Thangam
    Prodigy 20 points

    Hi Sasikala,

    I do not have the zoomed waveforms yet. When the Vds reached 1.5kV, it stopped within 1/2s.

  • 0 in reply to Tohfa
    TI__Expert 8065 points

    Hi Tohfa,

    If you can share the requested signals, zoomed in waveforms, it will help us to understand the failure scenario and support accordingly. Looking forward for your updated waveforms

    Thanks

    Sasi