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BQ24780S: Output cap selection

Antony Lin
Genius 13480 points
Part Number: BQ24780S

hi ,

Does it matter if we change the charger output Cap. size from 0805(10uF/35V*4) to 0603(10uF/35V*4)?

 

max charging current is 5.5A and the battery is 4S1P.

 

Thanks!

 

Antony

  • 0
    TI__Expert 5330 points

    Hi Anthony,

    The most important specs will be the capacitance, max voltage, temperature coefficient, operating temperature and tolerance.  You already mentioned the capacitance and max voltage (10 uF / 35V).  If the temperature coefficient is either X5R or X7R, the tolerance is +/-10% and the operating temperature meets the requirements, I don't see an issue with reducing the physical size.

    Other than the above, the main things that would be affected by package size are the parasitics, particularly parasitic ESL, but the inductor in the switching regulator is so much higher than the ESL of the output caps that this won't matter.

    Also, smaller package won't dissipate heat as well, but there should not be significant heat generated in these output caps.

    So, I think that this will be okay, but, as with any change from our reference design, customer should validate the change.

    Regards,

    Steve