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TPS40077 / input capacitor

K.Yaita
Guru 29720 points
Other Parts Discussed in Thread: TPS40077

Hi Team,

The datasheet shows 470uF electrolytic capacitor is required to maintain the voltage on the input rail.



However there isn't 470uF input capacitor in "EXPAMPLE APPLICATIONS(page.34-36)", it shows 22uFx2 only.
Could you tell me the background of the description?

Best Regards,
Yaita / Japan disty

  • 0
    TI__Guru**** 191445 points

    It is listed in the BOM for both the datasheet and the EVM Users Guide.  It is shown in teh EVM schematic as well.  The datasheet application schematics do not show it.  I cannot comment specifically for TPS40077, but I often use some bulk electrolytic capacitance when bench testing EVMs.  Even if the capacitor is not specifically included in the EVM, I have it attached to the end of my bench supply cable.  For typical POL applications, the TPS40077 (or other dc/dc converter) may be located close to the input supply source.  In that case, you may not need any bulk capacitance.  If it is at the end of a cable, you will most certainly get better performance with a bulk cap.