• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 417 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS53355 - minnimum Output capacitance when we use all ceramic capacotors

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: TPS53355

Hello,

Are there other requirement of minimum output capacitance without the equation (11) ?

 Equation (11)

L x Cout / (R7 x C1) > N x ton/2


I understood that the load transient specification are decreased with small output capacitors.
And, since the TPS53355 control is the DCAP mode , there is no stability problem if we satisfy the equation(11).
Thus, I believe that there is no requirement without equation (11).
But please allow me to confirm it. 

Best Regards,
Ryuji Asaka

  • 0
    TI__Guru**** 191445 points
    Equation 11 is not directly related to minimum Cout. Equation 11 is used to calculate the ripple injection components when using all ceramic caps on the output. Equation 7 sets the minimum output capacitance for stability (along with ESR). Otherwise the datasheet does not say much about selecting the output capacitor value. For a 30 A design, I would probably not consider anything less than a couple hundred uF.
  • 0 in reply to JohnTucker
    Guru 20090 points

    Hello John san,

    I would like to know the information when we use all ceramic capacitors.
    I think that the Equation (7) is not used for all ceramic capacitors.




    We should refer the "8.2.1.2.2 External Component Selection Using All Ceramic Output Capacitors" and it is equation (11).
    Is my understanding correct ?

    Also, could please let me know the problem when we use small capacitance for 30A application without load transient response, ripple?

    Best Regards,
    Ryuji Asaka