Author Topic: Calculating inductance for boost converter - units  (Read 5048 times)

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Offline newtekuserTopic starter

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Calculating inductance for boost converter - units
« on: March 04, 2024, 05:15:32 am »
Watching Phil's Lab video on calculating the value for the inductor and want to know what units he used to get the 23uH value for the inductor.


Vout = 16V
Vin = 5V
Eff = 0.8
Fsw = 1.5MHz

First he uses the estimation formula for the inductor ripple current =  0.3 * Iout (max) * Vout/Vin = 96mA

Then he feeds the inductor ripple current into the inductance formula (Vin(Vout - Vin) ) / Vout * f * IL = 23uH

Does he express the 1.5MHz frequency as 1.5 and ripple current as 0.096

OR

1.5MHz frequency as 1.5 and ripple current as 96, then multiplies everything by 1000 ?
 

Offline newtekuserTopic starter

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Re: Calculating inductance for boost converter - units
« Reply #1 on: March 04, 2024, 05:40:33 am »
Answering my own question: the frequency value is in MHz and the current ripple is in Amps

so (5 * (16-5)) / 16 * 1.5 * 0.096 = 23uH
 

Offline Berni

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Re: Calculating inductance for boost converter - units
« Reply #2 on: March 04, 2024, 06:15:36 am »
You are supposed to put everything into equations as base units. so the 1.5MHz should be 1500000 Hz and the result should be 0.000023 H

Just that since Mega is x1000000 and is on the bottom of the fraction so becomes /1000000 and Micro is /1000000 the units just happen to work out in a nice way, letting you work with numbers without a bunch of zeroes.
 

Offline Terry Bites

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Re: Calculating inductance for boost converter - units
« Reply #3 on: March 04, 2024, 02:07:13 pm »
I've used this handy tool. https://www.coilcraft.com/en-us/tools/dc-dc-optimizer/#/search
Give up on inches and farenheit.
 


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