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TPS53318: input Bulk cap concern

Ann_Lien
Genius 14360 points
Part Number: TPS53318

Hi expert,

My customer wants to apply 1*0.1uF MLCC+1*22uF MLCC+2*15uF POSCAP in their application. Condition is shown below. Do we have concern in our control loop based on this input capacitance combination? Thank you so much!!

Condition:

Vin=12V, Vout=5V, Imax=3.84A, TDC=2.688A, fsw=500kHz

Best regards,

Ann Lien

  • 0
    TI__Guru**** 191445 points
    Ann,
    There are three main points to consider with input capacitance.
    1. You need to make sure they can handle the RMS ripple current. Worst case it is Iout/2.
    2. You need to insure the input voltage ripple is acceptable.
    3. You need to get the input capacitors as close as possible to the IC.
    I would use 1*0.1uF MLCC+2*22uF MLCC+1*15uF POSCAP, but I think for 3.84 A output your 1*0.1uF MLCC+1*22uF MLCC+2*15uF POSCAP is sufficient. It really depends on your ripple requirements and the ESR of the POSCAP.