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UCC21710QDWEVM-054: PWM problem with EVAL board

Sumanto Bhatacrya
Prodigy 20 points
Part Number: UCC21710QDWEVM-054
Other Parts Discussed in Thread: UCC21710

Tool/software:

Hello,

I am encountering an unexpected behavior with my current setup and would appreciate your input.

I have slightly modified the evaluation gate driver to use it as LS driver only.

I’m using the SN65C1167ERGYR differential line receiver to convert a 5V differential PWM signal for interfacing with the UCC21710 gate driver. The differential PWM signal is a 5V, 10kHz pulse applied to pins 1 (A) and 2 (B) of the SN65C1167ERGYR. Please refer to the attached schematic for details.

The issue is that the single-ended output at pin 3 (R) remains stuck at a constant high level (5V), regardless of whether the differential PWM signal is present on the input lines or not.

Could you help me troubleshoot this behavior and point out any possible configuration or implementation errors I might be overlooking?

  • 0
    TI__Prodigy 170 points

    Hi thank you for submitting your question. A team member is out of office. We are looking into a solution now. 

  • 0
    TI__Expert 6710 points

    Hi Sumanto, 

    I've not encountered this before. Is your HS_PWM connected with LS_PWM anywhere (since in the EVM they are interlocked)? 

    Also, I would suggest depopulating R55 (the resistor connecting LS_PWM to the IN+ pin), then measure the LS_PWM signal. I wonder if there's an impedance mismatch that prevented LS_PWM from pulling low. 

    Thanks, 

    Vivian