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DRV8714-Q1: Short circuit detection when Powered Off Braking is enabled

RYO
Intellectual 2000 points
Part Number: DRV8714-Q1

Hi all,

I would like to know a little bit more detail about POB function. In the datasheet 8.3.8.2 "Low IQ Powered Off Braking (POB, BRAKE)", there was a statement of short circuit when POB is enabled as below:

In case of a short circuit to power supply fault present on the power stage, a simple overcurrent detector circuit with analog RC deglitch filter is provided to disable the low-side MOSFET if a high current event is detected while braking. This is needed since the normal overcurrent protection circuits are disabled during the device lowpower sleep mode. The overcurrent comparator and RC deglitch filter values are fixed and cannot be adjusted.

Is this the situation that the motor or SHx pin are shorted to the battery so that the low-side FET current is big?

Also, is the "simple overcurrent detector circuit" something like below? Can you present any examples about this?

Thanks,
RYO

  • +1
    TI__Mastermind 37683 points

    Hello RYO,

    RYO said:
    Is this the situation that the motor or SHx pin are shorted to the battery so that the low-side FET current is big?

    The overcurrent detector will monitor the VDS voltage across the FET. There is a fixed OCP threshold that will protect the output in the case of shorts like SH to battery.

    RYO said:
    Also, is the "simple overcurrent detector circuit" something like below? Can you present any examples about this

    The circuit consists of a comparator plus an RC filter similar to your schematic. The comparator threshold will be fixed along with the OCP deglitch time.