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TPA3118D2: Bulk capacitors selection in PBTL

Zeng.
Prodigy 90 points
Part Number: TPA3118D2

Tool/software:

Hello

I noticed that in TPA3118 DS the same bulk capacitance is used in SE and PBTL modes in the typical application example.I would guess that PBTL requires much less capacitance on the power supply. Could you provide a recommendation or a rule of thumb for choosing bulk capacitance in PBTL?

Also, how would you recommend to chose these bulk capacitors if known that the application requires just half the maximum power of the IC?

Thanks 

  • 0
    TI__Genius 9175 points

    Hi Zeng,

    Regardless of the output configuration, similar bulk capacitance is needed. You may be able to get away with more or less depending on the specifics of the design, but the two 100uF mentioned in the datasheet will be sufficient assuming design guidelines in the datasheet is followed. 

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Prodigy 90 points

    Hi Ramsey

    Thanks for the prompt response. My understanding was that power supply pumping is the major reason why so much bulk capacitance is needed. And as using a full bridge topology like in BTL decreases drastically the phenomenon, I'd expect its reflection on the requirements. Could you shed some light on where I'm wrong?

    Thanks

  • 0 in reply to Zeng.
    TI__Genius 9175 points

    Hi Zeng,

    You are correct that for a given system, you may be able to get away with a lower bulk capacitance in a BTL configuration. However, this will be dependent on your PCB (parasitic to the PVDD pin, trace impedance, ground return paths), and the audio output ( subwoofer vs tweeter will have different characteristics). The 100uF mentioned should be sufficient assuming decent board layout for all configurations and audio types the device is designed to work with. If values other than datasheet are chosen, then we cannot guarantee the same functionality as the datasheet since the system will be different.

    Regards,

    Ramsey