LMR23610: Cout and Inductance

Masaharu Takahashi

Expert 4170 points

Part Number: LMR23610

Hi, Team.

I've been asked by Customer to know recommended value(L and Cout) for below required spec.

Vin:16.5V

Vout:5V

Iout:30mA

As my calc, the below value looks ok but customer want to make sure how much value recommended from BU to select their inductance selection.

*50% current ripple is assumed.

193uH=(((16.5-5)/(0.03*1.5))*(5/(16.5*400*10^3)))

<Cout>

they want ripple on Vout would be within 100mV.

i believe that Cout(47uF) is good choice from datasheet. what do you think?

(Cout must be higher than 3.1uF and its ESR must be below than 100mOhm, correct?)

over 5 years ago

0 Neal Zhang over 5 years ago

TI__Expert 4720 points

Hi Masaharu,

It is recommended to use 22uH inductance. Because this IC is internal compensated, and the loop response is related to the inductance, so using big inductance will cause loop unstable.

Ref to datasheet, "Equation 12 to calculate the minimum value of the output inductor. KIND is a coefficient that represents the
amount of inductor ripple current relative to the maximum output current of the device. A reasonable value of
KIND should be 30% to 50%."

0 Masaharu Takahashi over 5 years ago in reply to Neal Zhang

TI__Expert 4170 points

hi, Zhang-san.

customer will see your answer.

the expected answer looks like below.

i was wondering if you could support that way, please.

uH~uH

Beacsue...

uF~uF (less than 〇mOhm ESR)

Because...

0 Neal Zhang over 5 years ago in reply to Masaharu Takahashi

TI__Expert 4720 points

Hi,

I saw your email and I will reply you there.

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LMR23610: Cout and Inductance