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DRV8243-Q1: Outputs state when driver is not powered

Paul SAUVAGEOT
Prodigy 10 points
Part Number: DRV8243-Q1

Hi,

I would like to know outputs state when driver is not powered. Indeed, datasheet indicates that driver outputs are in Hi-Z when for example SLEEP pin is active but I didn't find any information about outputs state when driver is not powered.

I would like to prevent any board auto-powering in case of regeneration if motor is moved manually on my system. I would eventualy avoid that by placing a diode (or other protection) on H-bridge power path but this takes some space on my board...

Thanks.

Best regards,

  • 0
    TI__Mastermind 44595 points

    Hi Paul,

    Thank you for your post. While the driver is not powered the FETs would not have any drive and the bridge FETs would be Hi-Z. However the MOSFETs have body diodes as these are inherent in their structures. These body diodes would conduct the motor generated output back to the VM when the motor is moved manually. This will be true for discrete MOSFEts based H-bridges as well. 

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 10 points

    Hi Murugavel,

    First, thanks for you answer.

    You're right, I didn't think to MOSFET themselves and their integrated diodes that run as classic H-bridge.

    So, I don't have really choice to avoid auto-powering, I must place something to block reverse current. I think to use an ideal diode controller (ex: LM74700) placed in series with H-bridge power path and eventualy combine it with a braking resistor to dissipate regeneration energy on bridge side. Do you think it would be suitable? Thanks.

    Best regards,

  • 0 in reply to Paul SAUVAGEOT
    TI__Mastermind 44595 points

    Hi Paul,

    Yes I have seen customers do similar schemes to avoid auto-powering. You want to consider auto-powering proving VM to the DRV. Be sure to have the driver disabled using DRVOFF  Braking resistor mostly dissipates the energy to avoid any VM powering with proper sizing.

    Regards, Murugavel. 

  • 0 in reply to Murugavel4637
    Prodigy 10 points

    Hi Murugavel,

    Okay, thanks for you return and warning for implementation.

    Best regards,