DRV8308EVM: closed loop at slow speed, running problem

Part Number:DRV8308EVM

Hi,

i want spin my motor with closed loop. Speed range is 100 - 1400 rpm.

Start always with load at 100rpm. 

The low starting speed is my problem.

The lowest start speed with closed loop i can realize is ~500rpm.

The Motor does not react if i choose a speed below 500rpm

My Motor: (4 Poles-Motor)

I use your TI development tool run the motor

this  are the register-settings:

Speed change over a external CLK from function generator.

Is it possible to run such kind of motor at closed loop with 100rpm with the DRV8308 at all?

Can you check the Registers... maybe i missed something.

Best Regards

Michael M.