• Resolved

DRV8876: DRV8876 - Independent Half-Bridge

Prodigy 70 points

Replies: 3

Views: 79

Part Number: DRV8876

I'm having a problem with the circuit attached.

The datasheet specifies the current capability as 3.5A of Peak, but when I test my circuit with a valve of 12V/0,5A , the fault pin goes to LOW and the voltage on valve fall to 0.4V.

I'd like to know if there is something wrong with my circuit? Any suggestion to resolve the problem.

Thanks

 

  • Hi Leandro,

    We need to go over the Fault table to identify where the fault comes from.

    1. Have you probed Vm and Vcp to see if they drop below the undervoltage values when the fault generates?
    2. Have you verified if the device recovers after the fault? That can be an indicator of OCP, possibly during an inrush current event.
    3. Lastly, we can also verify if thermal shutdown occured by analyzing the IC temperature. We can leave that one for last.

     

    Hector Hernandez
    Motor Applications Team

  • In reply to Hector Hernandez Luque:

    I'd like to know if there are some recommendations to control a valve in full-bridge (+VBAT=ON, -VBAT=OFF) operating in independent mode.

    OUT1 --- ( + VALVE - ) --- OUT2

    The following sequence does not work:

    (IN1, IN2)= (OUT1, OUT2)

    (0V, 0V) = (0.4V, 0.4V) for 0.25s

    (3,3v, 0V) = (13.8V, 13.2V) for 3s -> Wrong

    (3,3V, 3,3V) = (13.8V, 14V) for 0.25s

    (0V, 3,3V) = (0.4V, 14V) for 3s

    (0V, 0V) = (0.4V, 0.4V) for 0.25s

    (3,3v, 0V) = (13.8V, 13.2V) for 3s -> Wrong

    (3,3V, 3,3V) = (13.8V, 14V) for 0.25s

    NFAULT Stay Hiz in all condictions.

    If I use the sequence above the LOW SIDE of half bridge STUCK in GND.

    (3,3v, 0V) = (13.8V, 0.4V) for 5s

    (0V, 3,3V) = (0.00V, 14V) for 5s - Low Side Stuck to GND

    (3,3v, 0V) = (13.8V, 0.0V) for 5s - Low Side Stuck to GND

    After that both low side was Stucked in GND.

    Do you have any recommendation sequence or hardware protection control the valve and avoid damage on H-Bridge?

    Thank you.

  • In reply to LEANDRO SCHMITZ:

    I found the problem.

    Pin 9 is missing, It must be connected to VSS.

    Thank you for help.