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DRV8873: DVDD Pin not outputting 5 Volts.

Maanil Desai
Prodigy 30 points
Part Number: DRV8873


Hello,

I am using DRV8873H to drive a brushed DC motor (24V , 4 Amps). I am using it in the PWM mode. My issue is that I am not getting 5 V on the DVDD pin which is an internal regulator. I am getting 0 V at this pin. I have tied my nSleep pin to DVDD. Due to this I am guessing my device goes into sleep mode and is not responding to my IN1/2 signals from microcontroller. I checked the VM voltage. It is proper at 24.1 V. Upon giving an external 5 V trigger to the DVDD pin, the IC starts responding until I switch the main power OFF. Upon power ON, I face the same 0 V issue on DVDD pin. Kindly help me to resolve this issue.

PS: I have done all the connections and selected the external components as per the datasheet recommendations.

  • 0
    TI__Mastermind 37683 points

    Hi Maanil,

    Thank you for posting to the motor drivers forum.

    What is your power up sequence? 

    Have you seen this issue in other units?

  • 0 in reply to Pablo Armet
    Prodigy 30 points

    Hi Pablo,

    I am using a 24 VDC SMPS as primary supply to power DRV. This voltage is regulated to generate 5 VDC and 12VDC to power other circuits. Have used this regulated 5 V to pull up the nFault pin. I have currently tested 2 PCBs. Both of which had the said issue with DVDD pin. The DRV connections can be seen in the snap attached.

    I am using it in PWM mode with IN 1/2 (5 V) signals applied from a micro controller. 

    GND is 24V ground and GND_5V is 5 V ground. Both of which are separate and not shorted near DRV but at the regulator.

  • 0 in reply to Maanil Desai
    TI__Mastermind 37683 points

    Hi Maanil,

    Thank you for providing the information. 

    I understand what is happening. You have nSLEEP tied to DVDD. However, the internal regulator is disabled when nSLEEP is LOW. When you applied the 5V to DVDD, you basically powered up the device which enabled the internal regulator keeping the device ON until the power is cut off. I suggest tying nSLEEP to an external source.

  • 0 in reply to Pablo Armet
    Prodigy 30 points

    Hi Pablo,

    Right, That's something even I suspected :) Thanks for confirming.

    Will it be safe to tie DVDD pin to external 5 V supply permanently instead to dodge this issue? 

  • 0 in reply to Maanil Desai
    TI__Mastermind 37683 points

    Hi Maanil,

    We recommend not to permanently connect an external 5V supply to DVDD. If you end up re-spinning your design, I suggest connecting nSLEEP to external 5V supply.