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DRV8873-Q1: Short-circuit protection

Davide Ferrari
Prodigy 30 points
Part Number: DRV8873-Q1

Hello Support.

I use the DRV8873S-Q1 H-Bridge Motor Driver in one of my boards, in order to move a DC-Motor.

I'm facing problems understanding how the short-circuit protecion works. 

Is that correct to say that the short circuit protection works just when an over current protection is detected? 

Is there any other way that the circuit protects itself from a short circuit?

I also see a weird behavior after a OCP occurs. 

I'm using the driver in the "independent half-bridge" mode, forcing one of the outputs HIGH and using a PWM signal to control the other one, in order to move the DC motor either clockwise or anti clockwise.

The behavior that I don't understand is that after I connect one of the outputs either to VM or GND I read the DIAG status register, and the only bit that turns to 1 is the OCP_L1, no matter which kind of short circuit I apply.

I expected to see one of the other pins to turn to 1 (OCP_H1, OCP_H2 or OCP_L2). 

How do you justify this behavior? 

Thank you very much for your support.

Best regards. 

  • 0
    TI__Mastermind 44855 points

    Hi ,

    Thank you for your question.

    Is that correct to say that the short circuit protection works just when an over current protection is detected? 

    Is there any other way that the circuit protects itself from a short circuit?

    -> OCP is monitoring FET of DRV8873-Q1. OCP is detected by only over current on FET.

    I guess OUT(SH1) is shorted to VM or GND like following condition in you short test. So OCP_L1 only is not expected. (Itrip /current regulation -7.3.1.4 may impact this result)

    Good way to confirm is monitor current of SH1/SH2 and SH1/SH2 voltage (May check IPROPI as well). Then monitor nFAULT signal and trigger oscilloscope with nFault toggle.

    It is how we can normally check what happened when fault happened.

    regards

    Shinya Morita