MP6532 Motor driver not working

Hii there i have designed bldc controller using MP6532 drive ic,
i am using 20khz square wave pwm frequency from arduino nano, but motor is not responding to increasing duty cycle. it does not spin. i am applying 0.5v to OCREF. 470k dead time resistor. 1uf boostrap capacitor, 20 ohm gate resistor. 470nf/100v charge pump capacitor, 10uf vreg capacitor. brake, nsleep, DIR pin is either connected to 5v or open via jumper.

please review the attached schematic and help.