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TPS61088-Q1: Selection of the inductor and input capacitor

Part Number: TPS61088-Q1
Other Parts Discussed in Thread: TPS61088

Hi Helen,

When selecting an input capacitor, is there a relationship with the inductor?
Do you care about the capacitance of a capacitor? Or ESR?
Would you please advice?
best Regard,
  • Hello user6265022,

    There is not really a relationship to the inductor, but if you make the inductor smaller, the peak current increases, so the burden on the input capacitor increases as well. In general it is important that it is placed close to the IC to minimize input impedance.

    The ESR has to be small to minimize voltage ripple, so we recommend10uF capacitance with ceramic capacitors. Be aware of the DC bias effect of ceramic capacitors.

  • Dear Sir,

    Thanks Brigitte!

    The selection of inductor related to the Vin, Vout, Io and the operation frequency. For the boost converter, the selection of inductor and capacitor have no direct relationship.

    What is your Vin, Vo and Io? We can help to select the inductor for you.

  • Hi Helen,

    My design specifications are as follows.
    Vin=4.1V
    Vout=12.0V
    Iout=610mA
    What is the target capacitance and ESR?
    Best Regard,
  • Dear Sir,

    For the TPS61088 or TPS61088-Q1, ESR is not a must. So only ceramic cap at output side is also OK. 

    If there's no dynamic requirements, you can choose 2 pcs 22uF/25V/1210 ceramic cap at the output side.  if you need to choose smaller size cap, then you need to place more caps at the output side because of the derating under 12V DC bias.