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DRV8353: Question about PWM Noise and Bypass Capacitor of FET's Input

Intellectual 485 points

Replies: 4

Views: 56

Part Number: DRV8353

Hi, I am using DRV8353 for motor driver system.

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And found 20kHz PWM Noise from the board.

I put 1uF value for Cbyp, and Cbyp is about 3mm far from the High side Fet.

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Will this position will effect this noise? If I put this Cbyp closer to FET, then will it effect to reduce noise?

I think this is close enough but if this distance(3mm) will effect to noise then I will revision the board and make again.

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Or Should I change the value of Cbyp? Do you think Cbyp's position or value will critically effect to reduce the noise?

Or Any snubber circuit should be added? 

Thanks.

  • Seokmin,

    Thanks for posting on the MD forum!

    Where are you measuring the noise?

    Also your last image did not come through, is it the schematic?

    Regards,

    -Adam

  • In reply to Adam Sidelsky:

    Noise is came from the gate' signal.(GHA)

    This is same frequency of pwm, 20khz.

    Attached image is Drv8353's Datasheet. Page 66, Figure 63.

    There is simple block diagram of VM and Cbyp and FETS. 

  • In reply to Seokmin Hong:

    Seokmin,

    Which FET are you using? Which IDRIVE are you using? Do you have series gate resistors?

    Usually noise on the gate implies that the IDRIVE is not configured correctly because incorrect drive strength can cause gate/source oscillation.

    Regards,

    -Adam

  • In reply to Adam Sidelsky:

    Seokmin,

    I am glad that your issue was resolved but could you document the fix here please?

    Other customers will benefit from your advice :).

    Regards,

    -Adam

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