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DRV8885: Indexer

NAOKI AOYAMA
Guru 11215 points
Part Number: DRV8885

Hello,

Our customer use the DRV8885, have a question about Indexer.

The customer stop a motor at electrical angle as 315 degree, then nSLEEP Low to High (reset).

Does the electrical angle jump from 315 degree to 45 degree rapidly?

The customer have a one more question.

Is there any sequence between ENBL and STEP? Should the customer observe the timing as Figure 1?

Best Regards,

Naoki Aoyama

  • 0
    TI__Guru** 114905 points
    Hi Aoyama-san,

    The DRV8885 may move from 45 degree to 315 degree, or from 45 degree to 135 degree if STEP is logic high when exiting sleep mode.

    From section 7.3.3 of the datasheet:
    On power-up or when exiting sleep mode, keep the STEP pin logic low, otherwise the indexer advances one step.

    Is there any sequence between ENBL and STEP? Should the customer observe the timing as Figure 1?

    There is no sequence required between ENBL and STEP. There could be undesired movement if there is too little time between ENBL and STEP.
  • 0 in reply to Rick Duncan
    Guru 11215 points
    Hi Rick-san,

    Thank you for your reply.
    I explain the sequence of the customer.

    The customer use the DRV8885 with 1/16 STEP.
    STEP Low at 315 degree.
    nSLEEP Low (reset)
    nSLEEP High (re-start) , STEP still Low
    The electrical angle will be 45 degree.

    The customer want to know does it move from 315 degree to 45 degree rapidly
    when nSLEEP High.

    Regards,
    Naoki Aoyama
  • 0 in reply to NAOKI AOYAMA
    TI__Guru** 114905 points
    Hi Aoyama-san,

    It will take up to 850us typically, 1.5ms max for the device to move. This is the twake time.
  • 0 in reply to Rick Duncan
    Guru 11215 points
    Hi Rick-san,

    Thank you for your reply.

    I understood when the nSLEEP de-assert, it start from 45 degree after 1.5ms later.

    Thanks,
    Naoki Aoyama