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UCC28730EVM-552: burning board when monitoring gate signal on the EVM

romain viard
Prodigy 60 points
Part Number: UCC28730EVM-552

Hi,

I just burned my second EVM.

Can someone explain to me why i shouldn't put an isolated differential high voltage probe on the gate signal of the transistor. (It is roasting all the CS resistors (R9 R11 R12) making very nice electricals arcs....

Could you direct me to an application expert so that i can have my design checked? We designed an 9V 4W ACDC converter.

Many thanks.

Best regards

  • 0
    TI__Expert 8210 points

    Romain

    Our E2E threads are all supported by application experts for TI devices.  When you list a TI part number it gets assigned to someone who is an expert on that TI device.

    I can help you with this design.  You are correct to assume that you should be able to measure the gate signal with an isolated probe without any issue.  Something else may be causing this failure.  I'll need more information to help you here though.  Can you please provide the following information?

    • Confirm that you are using our EVM UCC28730EVM-552 and that you have made no modifications
    • Probe part number you are using
    • Description of all connections to the design (including source, load and all probes)

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 60 points

    EVM UCC28730EVM-552 from the box.

    Probe TESTEC SI 9002 (brand new)

    Only the HV probe (-) on TP3 (+) on TP6, source 230Vac, no load.

    At least R9-R11 were roasted, on a prototype board and 1 EVM.

    Many thanks.

    Best regards

  • 0 in reply to romain viard
    TI__Expert 8210 points

    Romain

    My understanding is that you are using "TT-SI 9002" that is in this spec sheet https://www.testec.de/en/assets/pdf/TT-SI/TT-SI-9001-9002_EN.pdf

    This differential probe is NOT isolated.  Depending on how your oscilloscope, input source and output load are grounded you may be inadvertently creating a current loop that can generate excessive current or voltage that is causing the failure.  We recommend that you use an isolated AC source and load if you use this probe.

    Best Regards,

    Eric