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TPA3130D2 output EMI snubber problem

Chee Ho Kar96
Prodigy 90 points
Other Parts Discussed in Thread: TPA3130D2, TPA3116D2, TPA3118D2

Hi TI,

I am using TPA3130D2 and follow the EVM datasheet circuit, but I got a problem on the EMI snubber circuit.

Refer to the EVM datasheet:

C100, R100 and C104 form a EMI snubber circuit, it use in TPA3116 and TPA3118 as well. But in TPA3130 it shows "do not populate".

I follow the datasheet to build the snubber circuit, the TPA3130 IC and the snubber's resistor become very hot.

Is that not possible to use snubber in TBA3130, or just needs to re-calcuate the value?

Many thanks.

  • 0
    TI__Genius 9175 points
    Hello,

    The TPA3116D2 and TPA3118D2 EVMs have full LC filters comprised of a wound inductor. Because of this, no PWM switching will be visible at the output since the filter cutoff frequency is specified to be well below the switching frequency of the device.

    For the TPA3130D2, a ferrite bead filter is used which will not filter out the PWM switching frequency. Instead, the ferrite bead filter will provide attenuation of only very high frequencies (90 ohms at 100MHz) required to pass EMI. Here the PWM switching will be passed through the ferrite bead to the output. Any load between the output and ground will see switching pulses equal in magnitude to the PVCC voltage. This includes the snubber circuit which is why it is marked as "Do not populate". The resistor power ratings would have to be very large in order to handle the power dissipation caused by the PVCC switching present at the output.

    You can experiment with larger value resistors to reduce current and their power dissipation as well. However, this may make the snubber circuit less effective a the frequencies where attenuation is required to pass EMI. In other words with this method, the results may be the same as leaving it not populated.

    Testing for EMI is the best way to test the effectiveness of these snubber circuits and what the best component values are to pass EMI.

    Best Regards,
    Matt Beardsworth
  • 0 in reply to Matthew Beardsworth
    Prodigy 90 points

    Hello,


    Thanks for your replay, it is very helpful.

    Best,

    Thomas