DRV8885: How to use PWM to adjust the chopping current?

James Zhan

Part Number: DRV8885

Hi team,

Could you please help to share how to use the PWM signal to control the chopping current in DRV8885?

Should we calculate the Voltage on the C1 and then use the equation 2?

Could you share the details calculation of Vc1?

Thanks.

0 Wang5577 over 4 years ago

James,

In equation 2, VDAC can be treated as the Vc1. When you know the winding current IFS setting and Rref value, you can get Vc1.

0 James Zhan over 4 years ago in reply to Wang5577

Wang,

I under stand the calculation from VDAC to get Vc1 in DAC mode.

But I am wondering how to calculate the Vc voltage when using PWM source with the RC filter here.

Thanks.

0 Wang5577 over 4 years ago in reply to James Zhan

James,

If the RC filter's time constant is longer enough, the Vc1= Vgpio * R2/ (R1+R2)=(Vmcu* PWM duty cycle) *R2/(R1+R2).

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