Inductor Selection help for varying voltage.

Thread Starter

DocQBN

Joined Jan 2, 2017
30
Hi there,

I'm trying to build a varying voltage supply (1.2-1.8) with the TPS548A20 by TI. I've been using their WEBENCH tool and have calculated for 1.2V I'll need a 1.5uH inductor and for 1.8V I'll need a 2.2uH inductor both @400kHz. I would like to keep Iout above 10amps. The voltage input will be either 12 or 5 volts. I looked at the datasheet to find the equation for the inductor and plugged that into a spreadsheet (attached). My question is when choosing the inductor, should I choose an inductor that meets my minimum Iout even though it has the ability to exceed my Iout rating on the IC? Should I be concerned with the frequency I choose? What's the best practice in this case?
 

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crutschow

Joined Mar 14, 2008
23,334
should I choose an inductor that meets my minimum Iout even though it has the ability to exceed my Iout rating on the IC?
You can as long as the peak inductor current will never exceed the inductor's current rating.
Should I be concerned with the frequency I choose?
A higher frequency allows the use of a lower inductance inductor, but possibly with a lower conversion efficiency.
 

Thread Starter

DocQBN

Joined Jan 2, 2017
30
You can as long as the peak inductor current will never exceed the inductor's current rating.
A higher frequency allows the use of a lower inductance inductor, but possibly with a lower conversion efficiency.
Ok, thank you. I figured that would be the best option I just wanted to see if there was a preferred method or some industry standard I didn't know about.
 
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