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LP-AM263P: Overcurrent detection using CMPSSA7 despite low ADC input

Burak Yeniaydin
Prodigy 220 points
Part Number: LP-AM263P

Tool/software:

Hi,

I want to implement overcurrent detection for a motor controller. I connected the analog output of my control circuit to the ADC3_AIN2 pin of the AM263P-LP. The value I read from this channel, as seen in the image, is 0x5CC.


I am using CMPSSA7. I verified in the reference manual that this CMPSS module is connected to the relevant ADC channel.


I also shared the values of DACH and DACL in the screenshot.

Despite all of this, I observe a high comparator trip, and COMPHSTS is being set.
I have also included screenshots of the CMPSSA7 configuration.


What am I doing wrong?

Regards,
Burak

  • 0
    Prodigy 220 points

    • I configured the negative input (IN−) of the high comparator to external pin INL (instead of internal DAC). This is physically mapped to ADC3_AIN3.

    • When I apply a signal to INH and a known reference to INL , the comparison logic works perfectly and the COMPHSTS bit is set as expected.

    • When I switch the negative input source from external pin INL to the internal DAC, the comparator doesn’t behave correctly.

  • 0
    Prodigy 220 points

    When I set the negative input source to the internal DAC,
    Here is the behavior I'm observing :

    • When I apply 0V to the corresponding ADC pin:

      • COMPLSTS → 1

      • COMPHSTS → toggles between 0 and 1

    • In other voltage conditions:

      • COMPLSTS → 0

      • COMPHSTS → 1

  • +1 in reply to Burak Yeniaydin
    TI__Expert 4230 points

    Hi Burak,

    Could you try with SW8 to position 2-3,

    This should fix your issue, if it doesn't let me know, I'll debug this further!

    Regards,
    Akshit