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DRV8837: about coast state

user1837178
Prodigy 20 points
Part Number: DRV8837

Hi,

I use DRV8837 in brushed DC driver.

The datasheet said the coast state could be either put nSLEEP pin low, or put nSLEEP pin high with IN1 and IN2 low. I wonder if these two operations are the same, since I want to save some MCU IOs.

Thanks a lot.

  • 0
    Prodigy 20 points
    For the nSLEEP pin, from Table 6.5 of the datasheet, the internal pulldown resistor is around 100kohm for DRV8837, does that mean if I use a pullup resistor of 10kohm with VCC=3.3, I'll get around 3.0V at nSLEEP, which will result a "always on" state on nSLEEP pin?
    And if I don't care the low power mode feature, this could still work for coast state if I put IN1 and IN2 low in my MCU code?
    Thanks a lot.
  • 0 in reply to user1837178
    TI__Guru 56650 points
    Zichen,

    In coast state, all power FETs are turned off (e2e.ti.com/.../the-art-of-stopping-a-motor).
    Putting nSLEEP pin low, or putting nSLEEP pin high with IN1 and IN2 low both can keep all power FETs off.

    nSLEEP pin is an input pin (check Pin Functions section). If the input signal is floating, it will be 3V with 10kohm pullup resistor. But, floating means the controller doesn't want to control the nSLEEP pin or a false control on nSLEEP pin.

    Yes. Putting nSLEEP pin high with IN1 and IN2 low can keep all power FETs off for coasting operation.