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DRV8424E: Does DRV8424E have inputs deglitch filter (might cause output jitter issue)?

Brian Dang
Genius 5040 points
Part Number: DRV8424E
Other Parts Discussed in Thread: DRV8701, , DRV8412, DRV8844,

Our original design using DRV8701 to drive a motor in PH/EN mode, but the input deglitch filters causes the output to have jitter which cause small audible noise when input pwm is not zero but constant; here is the link to the problem I posted about this: e2e.ti.com/.../4375137

We would like to use the DRV8424E instead, and the datasheet doesn't mention any deglitch filter for the inputs, but I want to double check with Ti engineers to confirm this.

Thank you,

Brian

  • 0
    TI__Guru 54695 points

    Brian,

    Yes, it does.  DRV8412 and DRV8844 do not have any deglitching on the inputs.  Could these devices be considered?

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    Genius 5040 points

    Hi Ryan,

    How do you tell if the DRV8424E has the input deglitch filter? I searched "deglitch" in the datasheet and found none except for the OCP filter.

    The 8412 is over-kill for the application, but 8844 seems to be ok.

    Thanks,

    Brian

  • 0 in reply to Ryan Kehr
    Genius 5040 points

    Hi Ryan,

    We prefer to use the DRV8424E which is available in smaller square 24pin package, compared to 28pin PWP larger package for 8844.

    So I need to confirm with the datasheet that 8424 has the input deglitch filter that could cause output jittering.

    Brian

  • 0 in reply to Brian Dang
    TI__Mastermind 28295 points

    Hi Brian,

    Ryan is out of office today and next Monday is national holiday in US. Please expect his feedback in middle of next week.

    regards

    Shinya Morita

  • 0 in reply to Shinya Morita
    Genius 5040 points

    Could someone at Ti use the DRV8424EVM in PH/EN mode, then input a constant pwm, i.e. 10% pwm duty, then check the outputs to see if the output pwm signal has jittering? I don't want to buy the $100 EVM board just to verify this.

    Thanks,

    Brian

  • 0 in reply to Brian Dang
    TI__Guru 54695 points

    Brian,

    It will have jitter.  How much...I am not sure.  But I think any amount is not acceptable to you which is why I suggested the DRV8844 which 100% does not have this input circuit because I defined the part. Slight smile

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    Genius 5040 points

    Hi Ryan,

    I appreciate the information. 

    Myself and I'm sure other users also would like to learn how to confirm which driver have the input deglitch filter, or none, by reading the datasheet, so what information should I look for in the datasheet? I am the designer and so I should have the documents necessary to justify the design. Sorry but taking your words is not enough to justify that 8424 has input deglitch and 8844 doesn't. The feature should be identified on their datasheet.

    I'm not working for Boeing or Lockheed Martin, but I'm sure you know that E2E posts is not a valid information for their design documentation.

    Brian

  • 0 in reply to Brian Dang
    TI__Guru 54695 points

    Brian,

    I agree 100% that this should be in the datasheet.  I will take this up with our system engineering team.

    Regards,

    Ryan