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DRV8834: nFault while SLEEP state

Torsten Rupnow
Prodigy 20 points
Other Parts Discussed in Thread: DRV8834

Hello,

I am using DRV8834 driver along with a stepper motor. I also use the SLEEP state of this driver. According to the datasheet I put the device in SLEEP state by driving the nSLEEP pin low. But for me it's interesting to know if the driver is in SLEEP state and the H-Bridge is disabled effectively. On oscilloscope I can see when the nSLEEP is set from high to low the nFAULT turns from high to low for around 1 ms. But after this 1 ms I could not differ between driver is in SLEEP state or not. Does the driver always drive the nFAULT pin for only around 1 ms when turning into SLEEP state. Is there a range of time perhaps 0.9 ms upto 1.1 ms? Is there an other way to identify whether the driver is in SLEEP state or not?

Thanks in advance for your help.

Torsten

  • 0
    TI__Guru** 114905 points
    Hi Torsten,

    What you are seeing is the internal logic being powered down. The datasheet discusses this when exiting sleep:

    When exiting sleep mode, the nFAULT pin will be briefly driven active low as the internal power supplies turn on.
    nFAULT will return to inactive high once the internal power supplies (including charge pump) have stabilized.
    This process takes some time (up to 1 ms), before the motor driver becomes fully operational.

    Examining VINT may meet your desire. It is disabled when entering sleep. The time may vary based on the variation of the recommended 2.2uF capacitor.
  • 0 in reply to Rick Duncan
    Prodigy 20 points
    Hi Rick,

    Thanks for the response. I focussed on the nFAULT pin only so I haven't considered VINT. That's the behavior I need. Thanks!

    Regards,
    Torsten