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Ringing on output of DRV8432

Hello, I am using the DRV8432 in my design, and I am getting a lot of ringing on the output at the solenoids, and motors that I am controlling. I have followed the recommended design that was given by TI, and I am curious to see if you have experienced this before. On the eval board there are inductors on the outputs of the driver. Can you tell me what they are used for? It seems that when I remove those inductors I still get some ringing, but it is much less. Below is a schematic of the circuit and the output of the driver at the load.

Thanks,


Rob

18 Replies

  • In reply to Rick Duncan:

    Hi,

    I am using DRV8432 in Parallel full bridge mode. I am getting a lot of ringing on the output at the inductors. Please share the snubber circuit which you have designed for DRV8432 and the location to place the circuit.
    I hope it may help me to get rid of the ringing.
  • In reply to sai77:

    I found this post that may be of benefit: e2e.ti.com/.../403063

    Rick Duncan
    Motor Applications Team

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  • In reply to Rick Duncan:

    Hello Rick,

    We're having the same ringing issue in our design.  We added the inductors at the outputs as short circuit protection, but due to the large ringing our motor current measurements show large spikes.  When we tested our boards after removing the inductors, the ringing peak to peak voltage reduced from 57V to 36V.  Per your response to Robert, the inductors are not required if the outputs not running in parallel mode.  We're considering to remove the inductors from our boards since we're running two motors in dual full bridge mode.  Could you please let me know if it would be OK to do that without any other consequences?

    Thanks,

  • In reply to rainbow:

    Hi Rainbow,

    The inductors are not required, but are recommended if you desire to protect the outputs against possible short circuits to high current signals (PVDD, GND).

    Please note section 7.3.2.2 of the datasheet. This section contains a recommendation to limit the current by adding a ferrite bead or inductor to protect the output pin against a short to power or gnd.

    Rick Duncan
    Motor Applications Team

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  • In reply to Rick Duncan:

    Hi Rick,

    Thanks for your prompt response! I have another question related to the ringing output. The datasheet shows that a snubber is added at the PVDD node on page 17. In our design we didn't add the snubber because the datasheet states that no external snubber of schottky diode is required on page 1. Don't we need the snubber in order to reduce the ringing caused by the inductors at the output?
  • In reply to rainbow:

    Hi Rick,

    I would appreciate it if you could respond to my question quickly because we need to complete our design very soon.

    Thanks,
  • In reply to rainbow:

    Hi Rainbow,

    The snubber is not required in all cases. Your application may be better suited for a snubber.

    If in doubt placing the footprints for the snubber is a good idea. If you do not need it, the component cost can be reduced.

    Rick Duncan
    Motor Applications Team

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                  Please Click the Verify Answer button on this post if your question has been answered.  Thank you
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  • In reply to Rick Duncan:

    Thank you for all your help, Rick!