Finally!

Neat. Kinda expensive, though (what from LT isn't). A mirror on that would be useful, too.

Yikes, I hadn't noticed the price. That's silly.

John

...

at would

Remember, you are seeing the simplified circuit. When you have protection circuitry, it has to be more complicated. And then nobody of any significance pays published prices.

Minimum load current of half a mA is a bit high for many applications.. you'd think they could do better with two resistors.

Best regards, Spehro Pefhany

In the world of discrete's, how much usage would it see? ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Yes, it needs work. But this is the first programmable current source IC that I know of, and it's been an obvious need for a long time. You could cascode this into an RF transistor and make fast ramps without a zillion parts.

Now maybe TI and OnSemi will do better ones for 15 cents or something.

I sometimes use the small Supertex depletion fets for this. Idss runs around 1.6 mA, and a source resistor will drop that to very low values. But current tolerance is not very good.

A multiple-output current source would be cute, too.

John

Once upon a time TI had a whole set of current mirrors. AFAIK, no more :-( ...Jim Thompson

How about an LM13700 and a resistor? You can have whichever polarity output you like.

Cheers

Phil Hobbs

Only one polarity, not very accurate and stupidly expensive, but they still have this one :

The old TI ones were these:

Best regards, Spehro Pefhany

I can use this sort of thing, but evidently I'm in the minority since monolithic arrays are going away and Darlingtons are dead. I got away with the MMBT3904 adjacent die parts last time around but my requirements aren't stringent for that circuit. We have another product that we had to do a one-time buy on a Zetex part because the product is dead without it and I'm not sure we *can* design around it (we certainly can't afford a chip). Maybe no one in the discrete world knows how to use current mirrors anymore.

What kind of tolerances do people really need? ...Jim Thompson

$3.50 a copy is not dime store. If I used such a thing it wouldn't be onesy/twosy, either.

I don't need that kind of tolerance (fortunately). 1% and $.15 would make me more than happy. ;-) LM385s are in the $.25 range.

Well, some people cannot count to one; once they get in gear for counting it is TWO late...

..

There are 10 kinds of people in this world, those that understand binary is not always the answer to a problem, and those that do not....

Steve

The 'whole set' lacked PNP mirrors, but included 1:1 through 1:4 and a part with multiple emitters that spanned 3:1 to 1:15

Never saw one, but they're in the old 1984-vintage linear catalog.

I still have a few left.

Cheers

Phil Hobbs