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DRV8873HEVM: DRV8873S IC - Short to battery and gnd will depends on motor direction?

Part Number: DRV8873SEVM

Hi,

OCP_L1=1 means short to battery and OCP_H1=1 means short to ground.

As the MOSFET is acting as high side switch so when short to GND happen it will detect OC fault.

Clockwise direction of the motor:-

OCP_H1=1 : Short to Gnd (OUT1 Pin of Driver)

OCP_L2=1 : Short to Vbatt (Out 2 pin of Driver)

Anticlockwise direction of the motor:-

OCP_H2=1 : Short to Gnd (OUT2 Pin of Driver)

OCP_L1=1 : Short to Vbatt (Out 1 pin of Driver)

Does this totally depend on the motor direction?  please comment.

Thanks and Regards

Ashish Nawani

  • Part Number: DRV8873SEVM

    Hi,

    Can you please confirm the scenario when the motor output is shorted to ground/ battery.

    1. If motor output is set to clockwise direction then the short to battery and gnd scenario.

    2. If motor output is set to anticlockwise direction then the short to battery and gnd scenario.

    How we come to know through SPI, fault reporting.

    And how we differentiate between short to battery and ground.

    Thanks and Regards

    Ashish Nawani

  • Nawani-san,

    Diag register can report which FET is shorted. For example: OCP_L1=1 indicates the bridge 1 output short to GND ; OCP_H1=1 indicates the bridge 1 output short to battery.

  • Hi Wang Li,

    OCP_L1=1 means short to battery and OCP_H1=1 means short to ground.

    As the MOSFET is acting as high side switch so when short to GND happen it will detect OC fault.

    Clockwise direction of the motor:-

    OCP_H1=1 : Short to Gnd (OUT1 Pin of Driver)

    OCP_L2=1 : Short to Vbatt (Out 2 pin of Driver)

    Anticlockwise direction of the motor:-

    OCP_H2=1 : Short to Gnd (OUT2 Pin of Driver)

    OCP_L1=1 : Short to Vbatt (Out 1 pin of Driver)

    Does this totally depend on the motor direction?  please comment.

    Thanks and Regards

    Ashish Nawani

  • Hi Ashish,

    If you are operating at 100% duty cycle, yes it depends on the motor direction.

    If you are PWM'ing, it does not depend on the motor direction.

    It depends on the FETs enabled. When the FET is enabled, the overcurrent circuit associated with the FET is also enabled.

    If the current flowing from drain to source is greater than the OCP limit for longer than the OCP deglitch time, the overcurrent circuit will flag a fault.

  • Hi Rick

    Thank you for the answer.

    Request you to confirm the following scenarios for 100% duty cycle: -

    OCP_H1=1 : Short to Gnd (OUT1 Pin of Driver)

    OCP_L2=1 : Short to Vbatt (Out 2 pin of Driver)

    Anticlockwise direction of the motor:-

    OCP_H2=1 : Short to Gnd (OUT2 Pin of Driver)

    OCP_L1=1 : Short to Vbatt (Out 1 pin of Driver)

    You can refer to the above-mentioned figure.

    Thanks and Regards

    Ashish Nawani

  • Hi Ashish,

    Confirmed for 100% operation, with the possible exception of a shorted winding.

    If the winding is shorted, then one of OCP_H1/L2  (clockwise) or OCP_H2/L1 (anti-clockwise) will assert. The first to assert will disable the outputs and may prevent the other from asserting.

    If this condition is suspected, operating the device in the opposite direction should also create an overcurrent condition in one of the two FETs.