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TAS5822M: Overcurrent protection problem

cai zheng
Prodigy 10 points
Part Number: TAS5822M

Hi  TI  TEAM

I would like to know that changing the 0.47uF capacitor to 2.2uF capacitor for the BST pin of TAS5822M chip will cause problems for the chip,

thanks!

Harrison

  • 0
    TI__Genius 15380 points

    Hi,

    can you tell me the reason why changing 0.47uF to 2.2uF?

    usually, 0.47uF is our recommendation. maximum value we used before is about 1uF.

    tks.

    jess

  • 0 in reply to Jesse Ji
    Prodigy 10 points

    Hi Jesse

    The reason is that Ti FAE asked us to change the BST foot into 1uf capacitor at the beginning, and there would be over-current protection during our production. Later, TI FAE asked us to change the BST foot into 2.2uf capacitor, and the test result was OK。

    We want to know whether the MOS tube inside the chip will be affected by changing the BST pin capacitor beyond the MOS tube Rds pin current。

    Thanks！

    Harrison

  • 0 in reply to cai zheng
    TI__Intellectual 1490 points

    Hi,
    many factors might affect OC.
    changing to 2.2uF do help solving problem, but according to our study, 1uF-2.2uF should not have that large difference.
    usually, 0.47uF should be enough.
    you can confirm below several things:
    1. what is your DC bias of BST cap? usually, we need it large than 7v.
    2. what is your inductor Isat of LC filter, it should be larger enough than your output peak current.
    3. have you connect the load when performing the test?
    4. have you tried using lower switching frequency?
    thanks.
    Donny