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BQ24195: Tantalum caps instead of ceramic ones

Alex Freed56
Prodigy 100 points
Part Number: BQ24195

The reference design (EVM board PWR193)  uses 22 uF ceramic capacitors C4, C15-C18. Since they are biased at 5 V, the actual capacitance is likely half of the rated one.  In addition the ceramic capacitors have piezo effect and can produce high pitched sound.

Is there any reason tantalum capacitors should not be used? I have substitutes tantalum 22 uF 10 V caps on one board and they appear to work just as well.

Thanks.

  • 0
    TI__Guru*** 143950 points

    Alex,

    Historically tantalum capacitor failure modes included combustion.  Newer tantalum capacitors now fail to an open.  Ceramic capacitors have very low ESR.  This low ESR results in very low large signal output voltage ripple and a small signal control loop zero that is too high in frequency to affect control loop stability.  If you choose newer tantalum capacitors that are similarly voltage rated and have low enough ESR (<=50mOhm), it should behave similar to a ceramic capacitor.

    Regards,

    Jeff