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DRV8711: Reset & /Sleep Operation

hideyuki sakai
Mastermind 6250 points
Part Number: DRV8711

Dear, Sir.

My customer is facing an issue using DRV8711.

The symptom is 48V VM Supply current is periodcally consuming

without the output motor driving.

We found the Reset & /Sleep is vaolating the 7.4 description that

when /Sleep is active, the Reset pin does not function.

So, I would like to make sure following. Please give your advice.

1. The timing would be like below the left side. What kind of issue will be ocncerned

   on the device operation? Does it show above symptom?

2. The right side would be correct timng, I believe.

  How much delay would be needed from /SleeoHigh to RESET=High?

  If I had a miss-understanding, Please point out.

Best Regards,

H. Sakai

  • 0
    TI__Guru 56650 points

    Sakai-san,

    Do you have any scope waveform to show the issue? The scope should monitor VM, RESET, /SLEEP and input current.

    RESET pin is an input pin. During the start up and /SLEEP is low, the RESET pin does not function. So, the right side would be correct. The datasheet said "When exiting from sleep mode, some time (approximately 1 mS) needs to pass before applying a STEP input, to allow the internal circuitry to stabilize." In this case, I would give 1ms delay for the internal circuitry ready.

    With the right side timing, does it fix the 48V VM Supply current periodically consuming issue?

  • 0 in reply to Wang5577
    Mastermind 6250 points

    Dear, Wang-san. 

    Thank you so much for your advice. 

    How much minimum duration will be needed as RESET=High for internal reset?

    Sorry again. I forgot to make sure. Please advice me again. 

    Best Regards, 

    H. Sakai

  • 0 in reply to hideyuki sakai
    TI__Guru 56650 points

    Sakai-san,

    Datasheet gives 10us TRESET Delay from RESETn high until serial interface functional. I would say please give minimum 10us for RESET signal.