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TPS22918: External cap reduction

Shinya Sawamoto
Expert 5295 points

Part Number: TPS22918

Hello application team,

I have 2 questions about TPS22918 external cap.
1. Is 0.1uF Cin sufficient? Or is there any problem when removed Cin at all close to TPS22918? (In this case, another 44uF is put on the same Vin line not closely.) 
2. When CT=0pF, is it possible to open the CT pin?
The client wants to reduce the total BOM cost as far as possible, so this is an important point to be judged TPS22918 or discrete.

Thanks in advance,
Shinya Sawamoto
TI Japan East area FAE

  • 0
    TI__Genius 15800 points

    Hi Shinya,

    1. The purpose of the input capacitance is to support the power supply during turn on. Specifically, there will be inrush current due to the output capacitance of the switch, and the power supply needs to be able to handle this current. If the supply can handle this, then the input capacitance is not necessary.

    2. Yes, if CT=0pF then the CT pin can be left floating (open).

    Thanks,

    Alek Kaknevicius