DRV8841: DRV8841 OCP issue

Part Number:DRV8841

Customer use DRV8841, meet OCP issue, the design follow DRV8841EVM. 

The max current through the motor is 1.3A, Risense is 0.36, Vref is 2.5V, so Ichop = 2.5/(5*0.36)=1.389A. 

Sometimes the motor will be locked, but the current is below 1A, and fault Pin output Low. Reset DRV8841 can work normal. the failure rate is about 2%.

Then we do another test, change the Risense to 0, test two days, don't repeat the issue. 

So we think the fault caused by OCP. 

Please provide more information, what condition will cause OCP, or OCP logic. thanks!