MCT8329A: How to increase VEN_SB

Hi

I have a problem with customized motor drive board using MCT8329, and I use the 8329A EVM to configure our customized boad.

I set the max speed 175Hz，use analog voltage to control speed, but I find it would trigger Loss of Sync when the analog voltage under about 400mv, and mct8329a will not work until I Power on again, and the customer can not use the gui to clear flaut.

and I have set ZERO_DUTY_THR:2.5% and ZERO_DUTY_HYST:6%, but it only make the VEX_SB be 255 mv

so, I wonder if I could let the voltage under 400mv not be transformed to nozero DUTY CMD to avoiding Loss of Sync.

or, is there a mechanism for recovering from a fault state to make mct8329a work again 

 thank you!