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Overcurrent protection in DRV8811

Alexander Vasiljev
Expert 1015 points
Other Parts Discussed in Thread: DRV8811

How overcurrent protection is designed in drv8811?

It seems that drv8811 in our circuit stops due to overcurrent protection. We need to know how it is designed to find a reason.

  • 0
    TI__Expert 7455 points

    Hi Alexander,

    The OCP is put in place to protect the device from hazardous scenarios such as shorts from output to output or shorts from output to supply (both GND and VM).

    If current is larger than 3A for a few microseconds, the device is disabled in order to protect against deadly current. The result is you do not see flames or smoke and the device can be made to work again once the deadly short is removed.

    That being said, there are some other ways in which you can inadvertently generate OCP events although there is no short present. For example, if you configure the ITRIP parameter to regulate current at values which are larger than the OCP threshold, and current can reach this point, then an OCP will be registered. Notice there is no real short across the outputs, but to the eyes of the device, there is a short. In this case, the motor winding is seen as a short because the current is just too high. This is the right thing to do because the FETs have a finite rating and we just can not put any given current. If the current is too large, regardless of the reason, the best thing to do is protect the device.

    If you get an OCP event, you will need to revise your design or application and make sure no hazardous conditions are present. Per example, if you see the metal chassis biting into the wires, you know the fix is to remove the short. If there are no short across the outputs, then it must be a too large ITRIP event. In either case, recycling power or recycling nRESET will clear the fault.

    Hope the info helps. Best regards,

    Jose I Quinones