• Resolved

DRV8802-Q1: Motor driver voltages on VCP pins

Prodigy 105 points

Replies: 7

Views: 99

Part Number: DRV8802-Q1

Hello Everyone,

We have developed working prototype using DRV8802 motor driver IC, after developing custom PCB we are facing some issues. We have compared voltage values on all the pins(on DRV8802) in prototype board and custom board and we see following differences

Pin Description Voltage on prototype Board Voltage on custom borad
VCP1 (Pin 1) 5.7V 1.78V
VCP2 18.26V 10.68V
VCP 25.34V 0-2.0V

The above values are taken at 13.5V supply voltage and the motors are not operating in the custom board whereas it is working in prototype board.

Request to help us in debugging this issue.

Regards

Brijender

  • Hi Brijender,

    Assuming you have checked multiple boards, this appears to be a problem with the new configuration.

    Please place nSLEEP low if possible and re-measure the CP2 and VCP voltages. VCP should be ~12V. If it is not, please double check the schematic, layout, and soldering of the board.

    Best Regards,
    Rick Duncan
    Motor Applications Team

  • In reply to Rick Duncan:

    Hi Rick Duncan,

    Thank you for the prompt reply, your suggestions helped us to further debug our board.

    In custom board we missed 1 Mohm resistor which is connected across Vcp and after soldering the resistor on the board we observe the following results

    At Input voltage(Vm) of 13V

    Vcp1 1.14V to 1.735V(while in operation) 
    Vcp2 10.65V t0 9.45V(while in operation)
    Vcp 12V (remians same while operating)

    Motors are still not operating. Following are the design accepts

    AVref = BVref = 3.3V

    AI0 = AI1 = BI1 = BI0 = GND

    IsenseA = IsenseB = 1 ohm

    Regards

    Brijender

  • In reply to Brijender Ramgopal:

    Hi Brijender,

    Have you examined the input signals?

    Is the device awake (nSLEEP = logic 1)?

    What is the V3P3OUT voltage?

    Also you did not confirm that you have seen this on multiple custom boards? Do all  custom boards behave this way?

    Can you provide a snippet of the schematic and layout showing the connections around the DRV8802? We can make arrangements to share them privately if necessary.

    Best Regards,
    Rick Duncan
    Motor Applications Team

  • In reply to Rick Duncan:

    Have you examined the input signals?

           Yes RESET,AENABLE, APHASE , BENABLE & BPHASE are controlled to MCU and on activation we have measures the voltages on the these pins.

    Is the device awake (nSLEEP = logic 1)?

          Yes the nSLEEP pin is connected to MCU GPIO pin and we have verified voltage across it is 3.3V on enabling the GPIO pins.

    What is the V3P3OUT voltage?

          Its 3.3V

    Also you did not confirm that you have seen this on multiple custom boards? Do all  custom boards behave this way?

       The first board is hand made circuit which is working fine second board is fabricated one which is not working, the only diffference is in the first one is configured for 71% of max current and the second one is        configured as 100% by configuring AI0,AI1,BI0,BI1

    Can you provide a snippet of the schematic and layout showing the connections around the DRV8802? We can make arrangements to share them privately if necessary.

         Please let me know how we can share the schematics with you.

    Regards

    Brijender

  • In reply to Brijender Ramgopal:

    Hi Brijender,

    Instructions have been sent. If you have not received them, please let me know.

    Best Regards,
    Rick Duncan
    Motor Applications Team

  • In reply to Rick Duncan:

    Hi Rick,

    I have recieved the instructions and also forwarded you the schematics.

    Regards

    Brijender

  • In reply to Brijender Ramgopal:

    Hi Brijender,

    Thank you for the instructions. For now, I will mark this thread as "TI thinks Resolved". You can still reply to the thread and I may update the findings if the community can benefit.

    Best Regards,
    Rick Duncan
    Motor Applications Team