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# TPS51123 [Choose the Output Capacitor(s)]

Other Parts Discussed in Thread: TPS51123

Hi

I have a question about"TPS51123 DataSheet P24[Choose the Output Capacitor(s)]"

I want to know the ”ESR” values necessary for the output capacitor.

It does out value even using Equation 8 under the following conditions,

I not out value. There is a thing to be considered something?

■Condition

Vin=12V、Vout=5V or 3.3V、

L=3.3uH

SWf=245kHz

Best Regard

T Kishi

• The required ESR value is determined by equations 1 and 8 in the datasheet.  Let me know if you have further questions.

• Hi john

Thank you for replay.
(1) Check from the equation.
However, I will not put out the value from the equation (8).

ESR={VOUT*20*(1-D)}/(2*Iripple)-(20*L*f)/2

Since this equation is "{VOUT*20*(1-D)/(2*Iripple)}" and "-(20*L*f)/2" =, the answer is "ESR = 0"
(8) Is there a way to find the "ESR" from the equation?

T Kishi
• hello,
there is a typo in equation 8.
it should be "ESR={VOUT*20*(1-D)}/(2*Iripple)=(20*L*f)/2", sorry for this typo

regards
Mike