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UCD3138A: DPWM signal's voltage level is not enough to let gate driver work(only 1 Volt)

Wilson Liang2
Prodigy 230 points
Part Number: UCD3138A

Hi Sir,

When we were investigating the LLC MOSFET burnout problem,we found that the signal output potential of UCD3138A's DPWMA/DPWMB was only 1V at random.

This is not enough to push the gate driver.


This phenomenon of insufficient potential seems to occur probabilistically, and does not appear abnormally.
Please refer to the attached pictures and videos, please assist in the investigation and analysis, t

hank you.

DPWM 1V

  • 0
    TI__Intellectual 1790 points

    Hello, 

    There are two possible directions. One is that it's caused by the external circuit. You could directly check the output on dpwm pins of UCD. The other is possibly caused by GPIO settings in the firmware. It's suggested that non-used GPIOs to output 0 in the firmware and connect to GND in the hardware. You could check if there are GPIOs that are configured to output 1 in the firmware but connected to GND in the hardware.

    Also, is there a scaler within the waveform? Because i noticed the scope div is 1V, and it seems the PWM-high is less than 3.3V, around 1.5V. 

    Best regards,

    Xuemei