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DRV8874: PMODE voltage level is not stable

Part Number: DRV8874

Hello Sir:

Please refer our tested report as below.

DRV8874 debug.pdf

That includes our schematic, PCBA and tested waveform.

Please refer e and f figure, we found the PMODE is not stable.

But according our schematic, our PMODE pin is pull high.

That effects OUT1 and OUT2 has output.

Would you please let us know why PMODE has this waveform?

Looking forward your feedback.

Thanks a lot.

  • Hey Statham,

    That is very odd.  The PMODE is an input to the driver, so nothing the driver is doing should affect it.  

    Your schematic looks good.  Thank you for the detailed info and oscilloscope captures. PMODE pulled HIGH will latch into PWM Control Mode. 

    I suspect an issue with the modifications done to your board - maybe a very small thin strand of solder/wire is lightly brushing PMODE to GND, causing the intermittent low signal?  I would try building up another board with all new components and see if the issue repeats itself.  

    Regards,

    Jacob  

  • Hello Jacob:

    Thanks your feedback.

    Looking forward your tested results on EVM.

  • Statham,

    Have you tested multiple boards? Our EVM does not show this problem.

    Regards,

    Jacob