LMR33610: Inductor cal?

kwon

Intellectual 920 points

Part Number: LMR33610
Other Parts Discussed in Thread: LMR33620, LMR33630, LMR36510, LMR38010

Hi.

What are the criteria applied to the L calculation formula in page.18?

If VIN=12V, VOUT=5V, fSW=400KHZ, K=0.3, and Iomax=1A, the L calculation is 24.3uH. How does L=8.1uH come out?

Even in TABLE9-3, the L value of 5V and 400KHZ is 8.2uH, and the L value of 1400KHZ is 2.2uH.

It is calculated as 24.3uH/6.94uH.

What is Iomax? Is it the max current of lmr33610 or the max current of the circuit load?

BR.

KWON.

over 1 year ago

0 Elena Gao over 1 year ago

TI__Genius 13735 points

hi, Kwon,

Notice LMR33610 is from family LMR33620/30. so the device calculation result is mostly like from LMR33630. Ioutmax could based on I limit .

Elena

0 kwon over 1 year ago in reply to Elena Gao

Intellectual 920 points

hi, Elena.

Is Iomax=Ilimt of 33610 and not an actual load current?

but, Calculated by Ilimtmax=2.9A, L becomes 8.38uH.

Calculated with Iomax=3A, L is 8.1 uH.

BR.

KWON.

0 Elena Gao over 1 year ago in reply to kwon

TI__Genius 13735 points

Yes, looking in DS the current limit is ~3A and more reasonable to get a 8uH inductor with 3A.

Elena.

+1 kwon over 1 year ago in reply to Elena Gao

Intellectual 920 points

Iomax is still confused.
13page Ioutmax=(Ilimt+Isc)/2, figure 9-4. Maximum Output Current vs Ambient Temperature says 1A.
Is it different from the Iomax in the above and the L formula Iomax?

And where is the current limit ~3A data sheet? I can't find it.

Is the link below wrong answer? Iomax answered 1A.

e2e.ti.com/.../lmr33610-inductor-selection-what-i_out-max-value-used-for-calculation

**And, The L value of LMR36510/LMR38010 DATASHEET was calculated as Ioutmax=1A, not limit.**

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LMR33610: Inductor cal?