Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 2462 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC21520: UL Verification About UCC21520

Cao Cao
Intellectual 770 points
Part Number: UCC21520
Other Parts Discussed in Thread: UCC27714

Hi Sir,

I plan Isolator Gate Driver application full-bridge resonant. and verification UL standard for Lab.

But we test short Drain to Gate of MOSFET, occur UCC21520 IC damage.

I thing is UCC21520 VOUT pin stress not enough, so I plan UCC27714D and ISO7340M.

since UCC27714D HB stress max up to 640V.

  • 0
    TI__Intellectual 2061 points
    Hello Mr. Cao,

    Can you please describe more details about the damage? I saw the package seems has physical damage? What is the difference between UCC21520 and Si8233?

    By replacing the UCC21520 with UCC27714+Digital isolator, I don't think it will solve the problem. You will see damage of UCC27714 or potential damage of digital isolator. The major reason is the HB-HS and OUTA-VSSA maximum voltage, and it cannot handle high DC bus voltage. please refer to the datasheet abs max table for more information.

    Using UCC21520, it will still maintain safety isolation when the output stage damaged due to the series isolation capacitor. Can you please review the app note: www.ti.com/.../slyy081.pdf
    and let me know if you have further questions.

    Thanks.
  • 0 in reply to Wei Zhang
    Intellectual 770 points
    Hi Wei,

    Thanks for your response. UCC21520 is OK but schematic has some risk when test short mosfet Drain and Gate.
    Do you have idea to improve risk of UCC21520 when high side mosfet short G-D pin? please comment.

    as I know first step PWM turn on low side fet then SW reference to GND.
    second step VCC charge bootstrop then turn on high side fet. this moment short high side mosfet G-D pin. Short though high/low side mosfet.

    summary when high side mosfet short G-D pin
    1. Out pin can damage by diode.
    2. Short though high/low side mosfet. damage mosfet.

    Cao Cao
  • 0 in reply to Cao Cao
    TI__Intellectual 2061 points

    Hello Mr. Cao, Thanks very much for your information.

    1. Can you please advise what risk in the schematic?

    2. With G-D short, it is hard to survive for the Low voltage from OUT-VSS due to the huge energy injected. Here are a few suggestions:

    a. add a TVS from G-S, which is not a zenner, this TVS can handle large current for instant energy discharge

    b. We also need to protect DC-rail. the power supply should be shutdown as soon as there is overcurrent when shoot-through happens. The current detection should be positioned between the DC electric bulky cap and bypassing ceramic cap.

    Please feel free to let me know if you have any questions.

    Wei