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UCC21750: Please suggest IGBT GATE driver that does not need additional signal for RESET

Jack Yang
Prodigy 20 points
Part Number: UCC21750

Hello,

UCC21750  needs \RST/EN signal to reset the fault output. For my application, we can not provide 

a signal from the processor to meet this needs.  I could add a timer delay after FAULT happens to  reset

it, however this adds possibility of false triggering. Could you suggest an IGBT gate driver similar

to UCC21750  that does FAULT reset automatically after a short delay? 

Thank you very much!

Regards,

Jack

  • 0
    TI__Genius 13760 points

    Hi Jack,

    We currently don't have a gate driver in our portfolio with the simple protection functionality as UCC21750 without the /RST signal to clear the detection of a short circuit event through the DESAT pin.

    One thing you could do would be to remove the need of sending the separate /RST signal by tying /RST to IN+ pin. Everytime IN+ goes low the driver would reset and taking both signal HIGH would enable the output. This would essentially remove the /RST functionality. This would be an automatic reset every switching cycle. More info can be found in section 9.2.2.4 RST/EN Pin Control section in the datasheet.

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    Prodigy 20 points

    Hello, Andy,

    Thank you for your response!  That concludes our search for a different TI gate driver. It is an interesting way to reset the driver though. However, 

    I don't think it will work for my application --- the responses to the DESAT sequence are: 1: DESAT causes FAULT to be LOW, 2: driver soft shuts down itself and  may (may not depending on driver circuitry design) shut off  PWMs to all other  IGBT drivers, 3: in our design, this LOW FAULT signal has to be maintained  for at last 200us for the DSP to shutdown all IGBTs and put device into a FAULT status.  4: after that DSP still waits for the FAULT signal to be back to HIGH before any new PWM switching --- we can not tie the /RST to the IN+ because of the way of our overall design (drivers and DSP), we will continue to test the added timer for the FAULT reset and hopefully UCC21750 is proved to be a good choice for our applications.

    Best regards,

    Jack

  • 0 in reply to Jack Yang
    TI__Genius 13760 points

    Hi Jack,

    The added timer seems to me to be the best option due to the needed time for the signal to be low, 200us. Let me know if you encounter any additional questions for UCC21750.

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    Prodigy 20 points

    Hi Andy, 

    Thanks a lot for your confirmation!, we will continue to test  to qualify the UCC21750.

    The plan is to use this driver core to run all kinds of IGBTs, such as CM600DX-24T1.

    Peak gate current is 8A, switching frequency is about 10khz, tested temperature increase 

    on this driver core is about 20C. For 60C environment around this chip, temperature

    of it is estimated to be 80C.  Besides peak current, and thermal increase, any other factors you may

    suggest me to consider (for driving different  ampere rated  IGBTs)?

    Thank you and best regards,

    Jack

  • 0 in reply to Jack Yang
    TI__Genius 13760 points

    Hi Jack,

    I don't think so. IGBT's are much more forgiving than other technologies (Super junction MOSFETs, Silicon carbide, etc...).

    • The gate voltage tolerance is important, but UCC21750 UVLO should accommodate a wide variety of IGBTs.
    • IGBT has a much longer short circuit withstand time meaning UCC21750 DESAT protection timing will also work for many IGBTs
    • Operating at 80C is far from corner temperature cases so I don't expect any abnormal behaviors from the gate driver.

    If UCC21750 does not seem suitable for specific IGBTs we have several variants within the family to test out. The difference between these device is external vs internal miller clamp, and different detection thresholds for DESAT short circuit protection.

    Best regards,

    Andy Robles

  • 0 in reply to Andy Robles
    Prodigy 20 points

    Thank you very much, Andy!

    Your answer is such good news to us --- we will continue the qualification process.

    Best wishes,

    Jack