LMR23630-Q1: Equation COUT

Shuji Ishiwata

Part Number: LMR23630-Q1
Other Parts Discussed in Thread: LMR23630,

Hi Team,

I have a question about LMR 23630-Q1.

Although it is equation (17) of a data sheet, I think that L is required.

I think the above equation is wrong. Is my recognition wrong?
If the data sheet is incorrect, please tell me the correct equation.

Best Regards,
Ishiwata

over 4 years ago

0 Samuel Jaffe over 4 years ago

TI__Mastermind 25590 points

User,

Equations 16 and 17 are used to calculate the output capacitance needed when accounting for load transients. The inductance and the inductor ripple has little effect on load transients since the VOUT droop is proportional to the output capacitance and the magnitude of the step.

You are correct that the output capacitor equation must include the inductor ripple when considering the output voltage ripple. This can be seen in equations 14 and 15.

-Sam

0 Shuji Ishiwata over 4 years ago in reply to Samuel Jaffe

Genius 5875 points

Hi Sam

I still do not understand.

It becomes 3.5F when the following value is input to this formula.

IOH = 3A
   IOL = 0.1A
   VOUT = 5V
   VOS = 0.25V

Is this correct? Capacitor capacity is too large.

L is written in the data sheet of LMR23630.
which one is correct?

Best Regards,
Ishiwata

0 Samuel Jaffe over 4 years ago in reply to Shuji Ishiwata

TI__Mastermind 25590 points

Ishiwata-san,

You are correct, my mistake. The LMR23630-Q1 equation should include the L term. This will be fixed in the next datasheet revision. Thank you for bringing this to our attention.

-Sam

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LMR23630-Q1: Equation COUT