1uH Inductor @ 3.3A

[wuchy143]

All,

I've looked into finding an Inductor from digikey/mouser and haven't had too much luck. I would like to have this inductor roughly the size of a 1/4W resistor. I will be using a lot of them on my board and don't want to lose too much real estate. Is this a technology limit or am I just not looking hard enough?

Thanks all

 

[Sceadwian]

https://www.electro-tech-online.com/custompdfs/2009/05/5300_series.pdf

Those are RF chokes though they may not serve your purpose as you haven't mentioned what they're used for.

 

[wuchy143]

Those are actually all I've been able to find. It says that the body size is .500" which is huge.

I"ve been asked to reverse engineer the filters we have been using on our keyboards. For power into my design(it's a keyboard...I think I've received advice from you before..so you probably remember me) we have been using 4 pin filters which are just pi filters. These filters were used on PWR and GND coming into the keyboards we have made for years.

RF chokes would be used in this application right? I want to attenuate RF into/out of my keyboard.

 

[Sceadwian]

Power inductors are always big. If you're just trying to filter RF out though are you really expecting it to be at 3 amps? What's wrong with the simple PI filters you were using? I remember you name now vaguely. I just hope the advice I gave you was okay <smirk> I'm horrible with remembering names. Some people have a mind like a steel trap, mine's more like a coarse sieve.

 

[wuchy143]

If you're just trying to filter RF out though are you really expecting it to be at 3 amps?

To be honest no. Our keyboards(at least the ones I've seen since I've been at my company) don't go any higher than 500mA. We used to have different LED's which sucked up much more than that but with LED technology the way it is today we stay under 500mA. Usually around 200-300mA is a good bet for current consumption on average for a 80 key to 121 key keyboard.

What's wrong with the simple PI filters you were using?

I don't see anything wrong with the filters we use as is. I was asked to reverse engineer them but didn't ask exactly why we would want to do that. I would assume it would give us flexability when going into EMI testing for mil-std 461. Also if they discontinued the parts(not sure if they ever will) we wouldn't be relying on them. Hmmm...time to talk to the big man I think.

As for your advice...not sure..don't 100% remember myself. But I've read a lot of your posts to others. I definitely respect your opinion..if that's says anything

 

[Sceadwian]

It's always good to have second source, and I bet mil spec certification is a pain in the rear, they require more than one source for everything and their tolerances make everyone suck it in =) Guess it depends on really what your goal is in the first place. Simply trying to outsource the same filters from another company or two may be possible. doing them in house may be as well. I'm not a filter expert, in fact it's probably one of my least knowledgeable areas in electronics, but you can reduce inductor requirements (hence size) by carefully chosing the rest of your components and the actual filter topology.