LM3410: How to compute Delta Il?

Julien D

Intellectual 510 points

Part Number: LM3410

Hi,

in lm3410 datasheet, page 12, equation 3 states:

Delta Il = (Vin / 2L) * D * Ts

in application note SLVA372C.pdf page 6 equation 15 :

Delta Il = Vin * D / (Fs * L)

as Ts = 1/ Fs, there's a factor 2 in those equations. Which one is the good one ?

Thanks

Julien

over 7 years ago

0 Clinton Jensen over 7 years ago

TI__Mastermind 25500 points

Hello Julien,

I can't find the app note you are referencing, but the equation in the datasheet should be correct. It's likely the datasheet calls Delta IL the peak from the average as shown in the picture in the datasheet. Perhaps the app note is referring to peak-to-peak ripple current which would be 2x the equation in the LM3410 datasheet.

Regards,

Clint

0 Julien D over 7 years ago in reply to Clinton Jensen

Intellectual 510 points

Hello Clint,

Here's the link to the app note.

Thanks

Julien

0 Clinton Jensen over 7 years ago in reply to Julien D

TI__Mastermind 25500 points

Hello Julien,

I was correct, the delta IL in the app note is peak-to-peak, that is the difference between the two. You will notice in the next equation it is divided by 2 to get the max inductor current.

Regards,

Clint

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LM3410: How to compute Delta Il?