Slightly OT - 5V regulator

Hi Gang,
OK, I'm designing a non flashlight circuit, but need a 5 volt regulator - of course, the old classic would be a 7805, or a , or a LMx17 set to 5v (as I have a whole bin of them - 10/$1 at the last hamfest). Anyway, I happen to be in a spot where power dissipation is an issue, and I KNOW in some past thread here I saw some pretty much drop in replacement regulators that dissipate a LOT less current - if I remember right they were a "switcher in a chip", but I'll be darned if I can find them

I NEED an output of at LEAST 16mA output (which would leave me with ZERO safety factor - my relays are rated for 80mW draw) - the GOOD news is I should never be pulling more than 1 at a time - so say if I can get 50mA, I should be good

Anyone point me to the right chip? (Man, I miss having my bookshelf of databooks - for some reason, I always have MORE problems when I have to search on the web - don't ask me)

What's your supply voltage range?

Here's one I've seen so far, not so much a chip, more a whole switching regulator in the same footprint.

http://www.dimensionengineering.com/

Supply voltage? In the 7-12 v nominal range, but call it 7-13.8 nominal range - most times, the end use will me 12v nominal, but there are some projects where I'd LIKE to go down to 7ish, and works would be "Car Battery" and all that implies (run away regulators when things fail, etc) - but the 90% case is regulated 12VDC

I guess your search is going to be for a "5 V switching regulator". Here is the first chip I turned up that seems appropriate, the MAX638:

http://www.maxim-ic.com/datasheet/index.mvp/id/1326

However, I'm sure there are other chips with similar specs.

Well... there are DC/DC converters if you really don't want to deal with the inefficiencies of a linear regulator
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtwaiKVUtQsNemMZL4TplJBqOl7845nWHA=
7-36Vin, +5V out 1.5A max...but likely you'll never need that high. 85% efficiency for about $4 before shipping.
It's alot cheaper than what dimension engineering gives, which I would only consider as a last resort

The MAX638 costs about $2.50/1000 (a quarter cent each), but I'm sure it will cost a bit more than that in single quantities.

Heres another one....Looks cheap and nasty but I've been using a couple of them for about 12 months without problems.
http://www.dealextreme.com/p/vmp3203-5v-high-efficiency-dc-dc-module-47817

Mr Happy said:

The MAX638 costs about $2.50/1000 (a quarter cent each), but I'm sure it will cost a bit more than that in single quantities.

Click to expand...

Eh... I think that is $2.50 a piece when you buy 1000 pieces.
I have used similar components from Maxim, and I don't believe the price will come under a dollar, even in large quantities.

@ only 50 mA, and if your load tolerates chopped DC, you could use a 555 timer at some freq. and vary the duty cycle to get your desired avg. DC value.

Lion251 said:

Eh... I think that is $2.50 a piece when you buy 1000 pieces.
I have used similar components from Maxim, and I don't believe the price will come under a dollar, even in large quantities.

Click to expand...

Oops!

Someone else saw the need too. At 10 bucks plus shipping I think it's more than you want to spend, but pretty neat.
http://www.ebay.com/itm/3-Terminal-...937?pt=LH_DefaultDomain_0&hash=item5d2691ffc9

Those OKI units at $4 work out fairly well - not unreasonable - $25 IS, but

Thanks all