*Hardware Help* Voltage Regulator

Sorry if this is a repeat post, I’ve looked around to no avail. I’d also like suggest that the moderators make a dedicated hardware thread for noobs like me.

I’m designing a pcb with a G120 SOM and I’d like to mimic the 5v voltage regulator off the old cobra 2. I need to pull just below 1 AMP and the old 7805 get’s too hot. I’ve attached the part I’m interested in using and I’d just like a little help selecting the parts from mouser please.

These are the parts I know I’m using;

http://au.mouser.com/ProductDetail/Micrel/MIC4680-50YM-TR/?qs=sGAEpiMZZMtitjHzVIkrqSWA8dCfXyljoBXEWlgcg9k%3D
http://au.mouser.com/ProductDetail/Kemet/T491D156K035AT/?qs=w5406s2IEAe%252bYOqqudmTaQ%3D%3D
http://au.mouser.com/ProductDetail/Diodes-Incorporated/B260A-13-F/?qs=%2Fha2pyFadug07TOrFOBcighkrOHM%2FseQBHaxLQdHO0g%3D

That just leaves the large capacitor and inductor I’m not sure about;
Would this be ok for the large capacitor?
http://au.mouser.com/ProductDetail/Nichicon/UWT1C221MCL1GS/?qs=%2Fha2pyFaduhGq%2FGfDIGjKvYFe87yqw1sGMzkZTQxNA%252b6hv4n01Tg8w%3D%3D

As for the Inductor I have no idea what so ever. But here is a link to the fixed inductors page; Also, a smaller footprint is better if possible
http://au.mouser.com/Passive-Components/Inductors/Fixed-Inductors/_/N-wpcz/

Thanks in Advance.

http://nz.mouser.com/Search/ProductDetail.aspx?R=CDRH125NP-680MCvirtualkey56750000virtualkey851-CDRH125NP-680MC

http://nz.mouser.com/ProductDetail/AVX/TPSD227M010R0150/?qs=%2Fha2pyFaduiIO4yyXl890HsrPr7EOGx7L%2FDkip5rnuQus%252byQSvSLaQ%3D%3D

Out of interest, what input voltage specs are you expecting ? That Kemet tantalum cap is only rated to 35v which after safety margin is down in mid 20’s, but the micrel part can work up to 34v… from your application you may well be using 24v input, so that’s all well within spec.

24 - 28v

Can someone explain why we use the more expensive cap. I’m budget conscious.

I assume you’re talking about the tantalum? If you want to shave costs, you can change the part around, but the reason for using a Tanty in the first place is usually lower ESR so you want to make sure whatever you’re using has a low ESR… plus, it’s often easier (and less expensive in the long run) in sticking with the regulator manufacturer’s suggestions :slight_smile: The Tanty is only needed on the input side so you’re only using 1-per board ?

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Is this ok. I’ve marked Tanty’s with a T, Electrolytic’s with an E, and MLCC with an M. If this seems like over kill I should explain. There will be 12 of these things spanning across a 28V rail that is will be about 50 meters long, in a noisy environment.

Or if you want to just buy something, how about this

I have a few of these and they work fine for this type of use.

It would be cheaper and easier. But I need to get it on the board.

Thanks Anyway.

Try Recom R78B series: http://www.recom-power.com/pdf/Innoline/R-78Bxx-1.0_L.pdf

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:slight_smile: :slight_smile: :slight_smile: :slight_smile: :slight_smile: :slight_smile: :slight_smile: :slight_smile: :slight_smile: :slight_smile:

That means I can swap out for 7805 when I don’t need the current on that model.

Legendary!!!

Thanks Everyone for the help.

7805 is widely used but it results often in a poor efficiency especially if your voltage input is much higher than the output voltage and that the needed current is also high… switching regulator is a “must have” but means also that EMI has to be taken into account…