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INductor selection for a buck convertor

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spanker1

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Hi,
I am working on a constant current control driver which outputs 1A of current. The inductor value for this design came out to be 25uH. Since i couldn't find an inductor 25uh with an Isat of 1.5 an above. I was wondering how high/ smaller i could go on inductance making sure that the current rating is high enough.

please advice
 

Dear spanker
Hi
As i understood you have a buck converter , with 1 A out put . right ? so what is your problem exactly ? can you tell me a bit more explanation , please ? thus i can help you .
Best Wishes
Goldsmith
 

goldsmith said:
Dear spanker
Hi
As i understood you have a buck converter , with 1 A out put . right ? so what is your problem exactly ? can you tell me a bit more explanation , please ? thus i can help you .
Best Wishes
Goldsmith
Click to expand...

Sure,

I am using NCL30160 controller chip from ON semi. We are currently driving our LED's at .5A using a 33uH. My boss wants me these LED's at 1A. Based on the Duty cycle and the switching frequency the inductance value came out to be 25.0uH for pulling 1A. I had a hard time finding an inductor with 25uH with an Isat of over 1.5-2A. So i don't know how much lower/ higher in inductance you could go?.. U think i could use an inductance value of 22uH with an isat of 1.7 instead of using the 25uH.

I hope this helps

Thanks
 

Why you don't try to wind an inductor yourself ? it is pretty simple . however i can't see huge different between 22 u and 25 u .
Good luck
Goldsmith
 

goldsmith said:
Why you don't try to wind an inductor yourself ? it is pretty simple . however i can't see huge different between 22 u and 25 u .
Good luckGoldsmith
Click to expand...

What kind of difference are you talking about.?.. please enlighten me.. I was thinking of using an 18uH instead of the 22uH.

thanks
 

With a buck converter, higher inductance is generally better, as the ripple current will be lower for the same switching frequency.

Finding a suitable inductor shouldn't be too hard. I'd be more worried about running the NCL30160 controller chip at it's maximum rated current.
 
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