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DRV8305-Q1: EMI

Genius 4090 points
Part Number: DRV8305-Q1

DRV8305NQPHPRQ1

Our csutomer did EMI test but their system.test result is attached.

EMI test result.xlsx

Large noise is found at DRV8305NQPHPRQ1.

When EN_GATE is high,large noise is found.

 When EN_GATE is low also large noise is found.

When DRV8305NQPHPRQ1 PVDD is off or  DRV8305NQPHPRQ1  is in sleep mode,Noise become reduced.

 Question1

Please let us know how to reduce noise other than above.

Question2

What circuit in this IC cause this noise ? What circuit in this IC is working at 59MHz or around 30MHz iwhen EN_GATE is low?

  • Kura,

    I am asking design about the blocks inside the device that are active when EN_GATE is low, I will get back to you in a few days.

    In the excel file, are these measurements taken with EN_GATE HIGH or LOW?

    Regards,

    -Adam

  • Kura,

    Is it possible for the customer to share the layout near the DRV so that we can take a look at the routing? We need to check if there may be EMI caused by capacitor placement or traces/vias.

    Regards.

    -Adam

  • Adam-san

    Thank you for your reply.

    I am asking to customer whether they can share their layout information or not.

    If you get design information about the blocks inside IC,please let us know it.

    Regards,

    kura 

  • Kura-San,

    There is an internal oscillator that runs at 58MHz inside the DRV, I am checking if this is spread spectrum which would help us reduce EMI.

    The main factor causing this type of noise is due to the AVDD and DVDD cap placement and layout, this is why we need to review this.

    Regards.

    -Adam

  • Hi Kura-san,

    The team is on holiday due to Memorial Day in the US, and will get back to you tomorrow!

    Thanks,

    Matt

  • Adam-san,Matt-san

    Thank you for your reply.

    Is there any other way to reduce noise other than shutting off the power and sleeping mode?


    EN_GATE:The noise level did not change with either H or L.
     
    Please let us know which cirrcuit in this IC is producing noise.

    What kind of circuit do you think is generating noise?

    You think that  It seems that the layout around AVDD and DVDD affects it,

    but when it is set to sleep mode ,will AVDD and DVDD circuit be cut off and the built-in oscillator also stop?
     
    They are connecting  AVDD and VREF in their circuit.Does this cause EMI ?

    They are considering whether to disclose the layout around the IC.

    When we got layout information from them,We will send it to you.

    Regards,

  • Kura-San,

    The internal oscillator is always running when the device is powered even if EN_GATE is low, this is why the noise persists.

    We will need to examine the AVDD/DVDD capacitor placement and layout to correct this issue.

    Regards,

    -Adam

  • Adam-san

    Thank you for your support.

    We got layout information from customer.

    Could you please let us know your email address ?

  • Kura-San,

    (redacted)

    Regards,

    -Adam