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TPS65219: Minimum output capacitance of unused DC/DC converter (Buck3)

Daisuke Sato
Prodigy 20 points
Part Number: TPS65219

Tool/software:

Hello

I am using the variant of TPS65219 with 07 suffix.

I only need 0.85V (Buck1), 3.3V (Buck2), and 1.8V (LDO2) to power my board.

The question is, do I really have to attatch the required minimum of 30uF as output capacitance to the output of unused Buck3?

I would like to reduce the cost and area by reducing the output capacitance to 10uF, for example.

Best regards

  • 0
    TI__Genius 9787 points

    Hello,

    Buck3 is part of the power-up sequence, so the proper 30 uF minimum capacitance is required.
    Buck3 is set to high bandwidth in the -07 configuration, so 30 uF is needed for stable output. 

    Buck3 would need to be disabled in the NVM configuration if wanting to leave this pin open.

    Best Regards, 
    Sarah

  • 0 in reply to Sarah Lao
    Prodigy 20 points

    Thank you for your reply.

    I understand that 30uF is required for stable output in high load situations and to maintain the specified performance figures such as load transient, line regulation, etc.
    But for no load, I suppose there may be a different capacitance limit.

    Also, I am aware that through NVM programming, Buck3 can be disabled, but I don't want to increase the work in the production process.