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TAS5822M: electrolytic capacitors for class-D

Part Number: TAS5822M


Could you help tell why electrolytic capacitors are not recommended for class-D applications? Thanks.


  • Hi Zach

      The electrolytic capacitors usually could have very large capacitance, but with larger parasitic impedance also bad linearity. It's size is also very big, may takes up large PCB area. With this characteristic, only the power supply side will use electrolytic capacitors, usually may need to use several hundreds or thousands uF. Although there maybe small value electrolytic capacitors, but with the side effect I mentioned, seldom to see anyone would use electrolytic capacitors with the value smaller than 10uF. 

      When using capacitor smaller than 10uF, most of the engineer will choose ceramic capacitors, as they have much smaller parasitic impedance and better linearity, makes the performance of product much better. At the audio using, better performance meaning better THD results, lower noise, etc. And the capacitor for LC filter of class-D amp, usually smaller than 1uF. No matter from cost, performance, or size, no reason to choose electrolytic capacitors.

  • Shadow,

    Thanks for the details. The reason why customer wants to try electrolytic capacitors is to avoid the MLCC piezoelectric noise.

  • Hello Zach,

    For power supply capacitance, electrolytics can be used on the power supply input which can be seen on our EVM. However, for the output L-C filter you cannot use them.

    best regards,