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DRV8412: In full bridge mode operation, no output when add capacitor between two channels or between channel and GND

user6219297
Prodigy 50 points
Part Number: DRV8412

I use DRV8412 to drive heater. PWM frequency is 1 KHz and without CBC. When I add capacitors between two channels or between channel and GND, no output and FLT pin is low level(I know it's OC status but can't reset it). DRV8412 can work normally after removing these capacitors. 

  • 0
    TI__Prodigy 460 points

    Hi, 

    We have a few questions: 

    1. What is the capacitor value? If too large, the OCP will trigger. 
    2. Is there an inductor between the output and capacitor? For high value capacitors this is needed. An example is the TEC application in the datasheet.
    3. Why 1kHz PWM? Could you increase to greater than 20kHz? 
    4. Could you provide a schematic? 

    Thanks, 

    Madison Eaker

    Motor Drivers

  • 0 in reply to Madison Eaker
    Prodigy 50 points

    1. Capacitor is 4.7uF + 0.1uF. And I try using 1uF + 0.1uF and have normal output.

    2. There is a 100uH inductor (1MHz) between output and capacitor.

    3. We use low-speed parts before DRV8412 because of cost. So we need low control frequency.

    4. My schematic is as below:

  • 0 in reply to user6219297
    TI__Prodigy 460 points

    Hi, 

    We recommend using the 1uF and 0.1uF cap. In addition, add a 5ohm series resistor between GVDD_x capacitor and GVDD_x pin. There will be four 5ohm resistors in total, one for each: GVDD_A, GVDD_B, GVDD_C, and GVDD_D. The resistors are used to limit in-rush current. 

    Thanks, 

    Madison Eaker

    Motor Drivers