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UCC21520-Q1: Gate driver Output Push-Pull being damaged.

Fabio Posser
Prodigy 225 points
Part Number: UCC21520-Q1
Other Parts Discussed in Thread: UCC21550-Q1

Tool/software:

Hi,

I’m experiencing issues with a PFC design connected to the grid, where the SiC MOSFETs are getting damaged.

After some investigation, we found that the output push-pull from the gate driver is short-circuited in some cases from VDD to OUT.

We have both PWM signals and a Disable pin coming from the microcontroller, but the timing for the Disable pin is not controlled because it can also be triggered by hardware protection.

According to the datasheet, the input should not be switched from ON to OFF during the turning ON process.

Does this mean the only way to work with this gate driver is by using an FPGA to control the turning ON/OFF and Disable of multiple sources?

Do you have any other part numbers to suggest that could handle this condition better?

Thank you.

  • 0
    TI__Expert 5876 points

    Hi Fabio,

    Fabio Posser said:
    According to the datasheet, the input should not be switched from ON to OFF during the turning ON process

    This statement in the datasheet is referring to narrow pulses being outputted by the driver. When a narrow pulse is outputted by the driver, it forces the output stage MOSFETs to switch while current is flowing through them leading to ringing and possible EOS. With UCC21520-Q1, as long as narrow pulses (time duration shorter than switching speed of MOSFET) is avoided there should be no issues.

    With the newer generation device, UCC21550-Q1, a pulse extension circuit is implemented. This additional feature prevents the output from outputting a narrow pulse by monitoring the gate voltage from the output pin. Since narrow pulses can be unintentionally inputted through the input due to external factors such as noise, UCC21550-Q1 would be a great device to completely prevent the output from switching while current is flowing through the driver's output stage MOSFETs.

    Link to UCC21550-Q1 product page: https://www.ti.com/product/UCC21550-Q1 

    I would recommend to look into this device, as it is a newer version of UCC21520-Q1 with improved robustness and a better cost structure as well.

    Hope this helps.

    Regards,

    Hiroki