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DRV10987: Over Temperature Warning Action Failure

Onkar Chichkar
Prodigy 10 points
Part Number: DRV10987
I am using DRV10987 for 12V DC Fan application.
And operating at 2+ A current most of the time.
DRV gets heated because of the high current.
There is a feature in DRV10987 regarding 'Over Temperature Warning'.
One can take action after over temperature warning has occurred.
Thus I have set the Current Limit to 1A on warning.
But current is not getting limited to 1A despite Over Temperature Warning Bit has set.
What might be going wrong in this case?
  • 0
    TI__Expert 6065 points
    I believe the current limit mechanism is the same as the Software Current Limit in the DRV10987 datasheet (www.ti.com/.../drv10987.pdf) section 8.4.7.1. According to the datasheet, "The software current limit does not use a direct measurement of current. It uses the programmed motor phase resistance, RPH_CT, and programmed BEMF constant (Kt) to limit the voltage, VU, applied to the motor". Thus if any of the previously mentioned parameters are entered wrong, the software current limit will be innacurate. Also, if the motor isnt being driven properly (which is indicated by the kt measured by the DRV10987, also called MotorKt register, not matching the user-entered kt), then the software current limit will not be accurate.