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DRV8889-Q1: Question on OCP and fault action

Scarlett Cao
Expert 4000 points
Part Number: DRV8889-Q1

Hi team

From my understanding for brush DC driver the OCP usually use to limit the inrush current during startup. For stepper motor driver which use current control, when does OCP usually happens? If OCP for thousands of time, will our IC degrade?

For the fault action like latch or auto-retry, can it be configured through SPI when output availble? Or it needs to be configured with output disabled? 

Thank you

Scarlett

  • 0
    TI__Mastermind 37683 points

    Hi Scarlett,

    You are confusing OCP with current regulation. They are two different features of this driver. This FAQ provide more details. 

    Current regulation is what limits the inrush current and regulates the current to a user set value. OCP on the other hand has a fixed threshold value and is meant to protect the driver from very high currents (for example when a OUTx to GND or VM occurs).

    auto-retry can be enabled via the OCP_MODE bit. setting it to b'1 enables auto-retry. Otherwise it is set to latch by default.

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    TI__Expert 4000 points

    Hi Pablo,

    Thank you, the FAQ is very helpful. Becasue our OCP retry interval is very short, so customer worries if they set to retry, will OCP be triggered continuously? Will repetitive OCP cause potential damage to the IC?

    OCP_MODE configuration must be done with driver output is enabled or it can be configured in real time? 

    Thank you

    Scarlett

  • 0 in reply to Scarlett Cao
    TI__Expert 4000 points

    To clarify the second question, there's a DIS_OUT bit on DRV8889, does it require DIS_OUT=0 to change other register setting like OCP_MODE?

  • 0 in reply to Scarlett Cao
    TI__Mastermind 37683 points

    Hi Scarlett,

    Scarlett Cao said:
    To clarify the second question, there's a DIS_OUT bit on DRV8889, does it require DIS_OUT=0 to change other register setting like OCP_MODE?

    The DIS_OUT does Not lock the register. You can make changes to the registers with the outputs enabled. 

    Scarlett Cao said:
    so customer worries if they set to retry, will OCP be triggered continuously? Will repetitive OCP cause potential damage to the IC?

    The outputs are re-enabled for the OCP de glitch time after retry time expires. The device is design to handle the repetitive OCP triggering. 

    Scarlett Cao said:
    OCP_MODE configuration must be done with driver output is enabled or it can be configured in real time? 

    The OCP_MODE can be adjusted in real time. 

    Regards,

    Pablo Armet