DRV8899-Q1: Unexpected OL failure

Hello Team, customer see follow behaviour:

- For initailziation motor will be driven with constant steps against blocking (0s..1.1s)

- Then current reference will be switched to hold current (1.125s...1.175s)

- Then current will be switched back to nominal current and 64 further steps executed (1.175s...1.3s)

- Then again switch to hold current.

At 1.3595s an OL error is detected on coil B (SPI read-out)

Current of Coils: Blue is B, Green is A

Any ideas how to explain this behaviour?

Many Thanks

Josef