Modern day 723 and 78xx for new design

[tkamiya]

In old days, if one was making power supply, he/she used 723 or 78xx.  But both of those series are quite dated.  What's the modern day equivalent? 

I need a low noise/ripple 24V 3A power supply.

[Wolfgang]

I had the same question. All the "good" new ICs are for lower voltages. If you find a *real* replacement for a 723, please tell me ! (but dont forget, I need 40V input, 150mA, ...).

[SiliconWizard]

Quite a few. Just to mention LT/AD: https://www.analog.com/en/parametricsearch/11536

Eg:
https://www.analog.com/en/products/lt1084.html
https://www.analog.com/en/products/adp7142.html

Now for those saying they are too pricy, go have a look at Alpha&Omega stuff.

[Wolfgang]

... not even close.
Where are the following 723 features:
- reference can be filtered
- long term drift spec
- settable current limit
- configurable compensation
- flexilibility to be used a spositive, negative, floating, ... regulator.
Why people still work with the 723 is:
- extremely flexible
- stable
- cheap like hell. 10€Cents in quantities, all "replacements" are some €.

[iMo]

723 works as a switcher too..

[Wolfgang]

... thats correct. I have never seen it in the wild, however. A lot of (older) units use TL494 or SGxxx type ICs.

[iMo]

This is a 723 switcher from a car charger (cigarette lighter adapter 14V->5V).

[Giuss]

I think that the 723 is still a very good chip

[Wolfgang]

Yeah, I use it a lot if I want something working and stable.

See here:

https://electronicprojectsforfun.wordpress.com/power-supplies/a-collection-of-proper-design-practices-using-the-lm723-ic-regulator/

or

https://electronicprojectsforfun.wordpress.com/silly-circuits/silly-circuits-a-heated-lm723-reference/

[tkamiya]

LDP 7142 and LT1084 are like LM317.  Not as cheap as 78xx and not as robust as 723.  Hum....  hard to imagine not much happened in 30+ years...

[schmitt trigger]

This is a 723 switcher from a car charger (cigarette lighter adapter 14V->5V).

WOW. A Harris semiconductor CA723. Nice vintage find.
Of course, a metal can uA723 would be an even better vintage part.

[Wolfgang]

The oldest ones I have are Harris military chips in CERDIP from 1986.

Photo here:

https://electronicprojectsforfun.wordpress.com/2018/09/18/not-all-lm723s-are-born-equal/

[Hiemal]

I got one!

http://ww1.microchip.com/downloads/en/DeviceDoc/mic5156.pdf

These are quite pricey, but they have the advantage of being able to use N-channel mosfets. The 5158 version even has a built in charge pump to ensure proper gate drive, something that I feel is pretty unique.

[coromonadalix]

Here is a very nice and well done project by velleman
The K7200 kit  0-30v 0-10 amps power supply

The 723 can make good psu's, it's still in production

https://www.velleman.eu/downloads/0/manual_k7200.pdf

[tkamiya]

I think I'm going to use LM317.  Load regulation 0.05% and ripple is 0.5%.  That's about 1.n mV at 24V.  Not bad for simple circuit.  7824 on the other hand is order of magnitude worse.

[iMo]

What is the IC3 in the Velleman's kit?

[iMo]

You will not get 3A out of an 317..

[markce]

What is the IC3 in the Velleman's kit?

Another 723

[coromonadalix]

yep  dual 723 regulators
one for voltage and one for current

[DaJMasta]

You will not get 3A out of an 317..

Sure you can, you just feed it the minimum voltage above dropout and put on a decent heatsink

[mariush]

No, most 317 regulators are advertised as 1.5A regulators and they have a "typical" current limit at around 2-2.2A ... maybe you can use an extra transistor to get 3A but just with the regulator alone, 3A ain't happening.

[iMo]

The 317 recommended max Iout is 1.5A. For 3A you need an extra pass transistor over it (plus some basic overcurrent protection), or to run 2x317 in parallel (with some care}, or to use the LM338 (5A version).

[David Hess]

Nothing has replaced the 723 and it is still in production.  The 317 is a general improved replacement for the 78xx series.  Improvements over the 317 and 78xx series include the LT1086 which is available in fixed and variable versions.

There have been other improved 78xx and 317 parts over the years but none caught on as much as the LT1086 and similar 3-pin parts.

[Wolfgang]

People have tried to replace the 723 with better chips like the SG3532,  ...
they had thermal protection, lower voltage references, better current limiting, ...
but they could not match the 10c per chip, so nobody bought them and the vanished from the market.

[battmyrne216]

nice example from an elenco power supply that used the 723. Edit: actually this schematic only uses the lm317. but the elenco I had happened to use the 723. Ive found its version schematic before but now im gonna have to find it.