Linear 5V reg with adj.current limit

ON Semi has it. So does JRC, under the name NJM723. Not sure if it was KEC (Korea) but I've seen another Asian source.

Digikey has over 10,000 from ST in stock and no obsolescence warning. Haven't checked ST because their web site is the pits.

But no adjustable current limit which is what the OP wants. If I needed fairly precise current limit and it was all on a tight budget I'd try to use a TL494 as a linear regulator. That thing will likely be around until you and I can't hold a soldering iron no more.

ST is showing it in active production,

Cheers

Phil Hobbs

Companies such as PowerOne are buying those things by the bucket. I have yet to see an OEM linear brick supply that does not have a 723 in there.

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Considering that they work okay, and cost 16 cents in quantity 1, I'm not surprised.

Cheers

Phil Hobbs

Oops, must have hit on a non-RoHS version or something. That's good!

I have not seen Chinese clones as with some more modern parts, but then I have not really been looking.

Best regards, Spehro Pefhany

STMicro still has the L200

Sure, that's got to big one... any idea how many of the old-style linear supplies they make a year? Looks like the design has not changed since the 1970s.

Best regards, Spehro Pefhany

putting the entire output current thru the pot wiper is troubling.

Not as troubling as the blue smoke and Joergish noises coming from the resistor element when it's set below about 1/4 scale. ;)

Cheers

Phil Hobbs

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As well as undefined bias state, and noise from bouncing in and out of "drop-out". Interesting problem... how do you do that with stability and predictability? ...Jim Thompson

Does that mess come with a fire extinguisher?

Most use current limiting just for protection. It doesn't have to be "that" accurate. Remember, it is yet another control loop. Less is more!

Funny thing is with TI buying up companies, there are less choices in regulators. They have Unitrode and National. Maybe I left one out.

Oh yeah, 723, good stuff.

Thanks for all the replies.... I didn't quite express myself correctly.... I should have said 'selectable' as opposed to 'adjustable'. The adjustable solutions require too much effort ( for these simple test box setups). The optimum was mentioned by a few and thanks- I'll go with the 317 (actually 1117DT) and current limit resistor with adequate wattage for each solution. The pot idea was good but would need a 2W+ pot lol. My favourite 5V reg is the LM2940.. The reason for current limiting is to prevent 'smokers' if there is a short on the UUT.... due to piss poor inspection :)

Power Trends, maybe Benchmarq if you count them.

Best regards, Spehro Pefhany

And one must remember if using a rotary switch to select in/out resistors the network should be in series, connected between each pole so that when the pole contact leaves the nest as it's moving on towards a new home, you don't get a totally open circuit.

Jamie

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No idea, but considering that Digikey carries over 500 just of this model in stock means it must be selling at a pretty good clip:

I never had a leadtime on any, and I or my clients have bought lots of different voltage versions. They are very convenient for test gear because you don't have to worry about noise. Plus it's almost guaranteed to contain the old 723 so it's very stable. Meaning no worries about an iffy load or instability during brown-outs.

Michael, On paper, it works. However, how that LM317 "floats" is indeterminate. Possibly it just saturates up against the positive rail until current limit is reached. ...Jim Thompson

The L200 used to exist. A 5 pin TO-220. Like a 317 with a adjustable current limit set by external components. SGS-ATES, maybe ST now.

Rather low power dissipation, so putting too many volts in was problematic. With a higher (than a LM317) dropout voltage, too.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

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Yeah, I've occasionally used those in onesy-twosey, last time was a couple months ago... didn't want to risk having to fix EMI problems from a SMPS in a sensitive electromechanical test setup. TO-3 transistors (hermetic) even, and single-sided board. You just put them in and they work (at least until that 85°C cap dies).

Probably lots of small volume legacy gear uses them too. Just curious as to what that might add up to. Heck, you can still get new LM741 parts, and I bet nobody has designed that one into a new piece of volume gear in over a decade.

Best regards, Spehro Pefhany