DRV8307 CW/CCW error when slow down

Hi,all

We are using DRV8307 as our motor driver, but encounter some problem.

1.when slow down the motor, there is an chance that the motor suddenly out of phase.

2.different reaction above between CW and CCW. 

we have using both EVB and our own board, but both have the same problem.

we have an video clip on youtube to show the problem here:

(Please visit the site to view this video)

Best regards,

Will