LM723 replacement

Looks like the venerable LM723N  inear regulator chip is now obsolete (it lasted 50 years). It was great because it contained all the basic building blocks for a lnear reguklator of any voltage and current.

Question is what is the modern equivalent? (In a DIP package please)

Cheers

Ian

Good luck... just looked at TI and their only 16 pin package regulator is SMD.

JR

I've bought other chips from these guys before and it was all good.....

Not sure it helps.....didn't look at the types.....

https://rcfreelance.com/search.php?q=lm723&x=27&y=9

Maybe :
https://www.nteinc.com/specs/900to999/pdf/nte923.pdf

https://www.futurlec.com/Motorola/MC1723CPpr.shtml

edit: https://www.tme.eu/en/katalog/#search=nte923&cleanParameters=1

I expect modern regulators to be superior performance compared to the old dog 723.

JR

I guess all of the manufacturers of the "open frame linear" power supplies (like Power-One, International Power, etc) will have to revise their tried-and-true designs.  Every one I've seen used a 723 DIP.

Bri

The TI LM723 is still active for the TO-99 package, but the TI uA723 is the part number for the DIP and SOIC package, the direct replacement for the Fairchild µA723. I have not studied the spec sheets in detail, but it seems that the uA723 is basically same thing as an LM723, so the world will not end just yet.

Mouser has only 12,000 of '723 in 14-DIP. Buck/each, but half-buck in hundreds. If you can't easily amortize a re-design, maybe time for lifetime buy?

PRR said:

Mouser has only 12,000 of '723 in 14-DIP. Buck/each, but half-buck in hundreds. If you can't easily amortize a re-design, maybe time for lifetime buy?

Click to expand...

Oh, how I love search engines! What started me off on this trail was this result from Mouser:



Cheers

Ian

For a "new" design there are much better modern parts...

I haven't used the 723 since the 70s and don't recall any features that I miss...

Several features in modern parts that I would miss.

JR 

For a "new" design there are much better modern parts...

Click to expand...

Any suggestions on what to browse/ look at?

Martin Griffith said:

Any suggestions on what to browse/ look at?

Click to expand...

Back in the old days there were few choices.. now there are many.

What is your design requirement?

If dropout voltage is a factor check out the category of LDO regulators.

For battery use check out some modest current drain CMOS regulators.

High voltage, low voltage, high/low current, low output impedance, low(er) noise, so many choices.

But I repeat the ua723 and old LM100 were products of the semiconductor technology available at the time,( decades ago).  Now you can make reasonable adjustable output regulators from specialized 3 terminal vreg... 

Over temperature and short circuit protection are standard in modern parts.

Old parts were more fragile.

JR

The letters on the end may be critical. However TI's one datasheet for the '723 is not loading, and another is from 1999 and may not have the latest changes. I'm pretty sure the one version I showed is a classic DIP and there is plenty in-stock for DIY or small production. ALL of the DIPs are going out of production: falling demand means the DIP machinery gets shoved in the alley to make space for SMD machines.

The '723 is bag of parts in a small box. While many connections are internal, you still have to do a lot of external wiring. It has pins for boost and current-limit, you can do V/I slope limit, but it does not have *thermal limit*. When working recklessly, it can be killed. For convenience and robustness, the 3-pins have it beat. If you want something more complicated, the '723 *may* be a handy building block.

And of course if you have been making the same thing since 1977, have a lifetime supply of DIP-14 PCBs, you probably are keen to keep getting the old-school bugs.

What is your design requirement?

Click to expand...

I'm half heartedly playing with  Linear's LT1533, (using the wrong transformers of course) to work off a single Li_ion cell, to give low noise 15-0-15 ish volts. maybe P48 as well.
I've milled out a PCB, just got to populate it, and evacuate the magic smaoke

AN70 from Jim Williams at Linear is a lovely read.

Martin Griffith said:

I'm half heartedly playing with  Linear's LT1533, (using the wrong transformers of course) to work off a single Li_ion cell, to give low noise 15-0-15 ish volts. maybe P48 as well.
I've milled out a PCB, just got to populate it, and evacuate the magic smaoke

AN70 from Jim Williams at Linear is a lovely read.

Click to expand...

I am not sure what a switching regulator has to do with a 723 thread, but to square that circle, back in the 60's my first technician gig was working on a switching PS in a NAVY project. That design used a LM100 linear regulator, tricked into oscillating and being a switcher..  :

JR

Hi Ian,.
If in doubt, check in China - aliexpress
Their fabrication is getting better all the time!
I've probably had 25-30 orders of varying things,
pcbs,passive components, connectors, transistors, old .like bbd's and opamps, and assembled modules.
All been good with the exception of some crappy connectors, but hey! - I've had crap from closer to home!
A lot, if not most stuff is fab'd in China, shipped over and re-badged anyway!

Only down side is shipping can be up to 2 or 3 months stated. Funnily enough, my last order has still to arrive
and that was 5 weeks ago. Somethings  prior had been delivered in 2 -4 weeks, and up to mid Dec some orders
were landing in less than a week!!

Here's the link -

https://www.aliexpress.com/wholesale?catId=0&initiative_id=AS_20190122143312&SearchText=lm723cn+voltage+regulator

Oh!! - also - can be stupidly cheap!!

JohnRoberts said:

Back in the old days there were few choices.. now there are many.

What is your design requirement?

JR

Click to expand...

Tube HT supply. Rough smoothed 300V dc input. 250V at up to  300mA regulated very low noise output. By very low noise I mean ripple in the micro volts (on the order of 90dB ripple attenuation).

Cheers

Ian

ruffrecords said:

Tube HT supply. Rough smoothed 300V dc input. 250V at up to  300mA regulated very low noise output. By very low noise I mean ripple in the micro volts (on the order of 90dB ripple attenuation).

Cheers

Ian

Click to expand...

I suspect this has been thought about already (I am not the tube guy here), but remember the regulator cares about voltage relative to it's own ground lead, not actual ground, so you can float the regulator up as high as needed (zener in series with ground lead or whatever). 

For low ripple perhaps consider a post regulator, more like a capacitance multiplier to use active gain to reduce noise.

I will not insult the tube guys around here who have probably already investigated this stuff..

JR (not the tube guy).

Oh geez, yet another part in the latest 3rd Edition of "The Art of Electronics" dies. The others I was looking for from the book were JFETs.

The chapter on power supplies just happens to be available as the "sample chapter" and the guys seem to like this venerable part:
https://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf

The "Power One" and other open-frame linear supplies all seem to use this part, it seems a good idea to stock up just for repair/replacement use.

Check the rest of the thread - this part is not EOL - all is well! TI eliminated one part number, but they continue to sell other equivalent part numbers (uA723), and if you have deep pockets, you can buy the space grade LM723, or the TO-99 packaged commercial LM723.