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Better alternatives to the LM317A?

post #1 of 19
Thread Starter 
Hi,
this question just came into my mind: are there alternatives to the LM317A which provide better regulation? Yeah, I could [edit: build not buy] a Jung superregulator, but something with the simplicity of a TREAD but with better specs would be nice. Should be able to handle large capacitances at the output, so a LDO chip will most likely not be suitable. Pin-out compatibility is not needed

Does anybody know of such a replacement for the LM317A?
post #2 of 19
Quote:
Originally Posted by balou View Post
Hi,
this question just came into my mind: are there alternatives to the LM317A which provide better regulation? Yeah, I could [edit: build not buy] a Jung superregulator, but something with the simplicity of a TREAD but with better specs would be nice. Should be able to handle large capacitances at the output, so a LDO chip will most likely not be suitable. Pin-out compatibility is not needed

Does anybody know of such a replacement for the LM317A?
Believe me, if there were something simple, I'd be the first one in line.
post #3 of 19
Possibly a shunt regulator like TL431? I don't know a lot about these and the specs are not directly comparable, but they seem to be popular. Completely different topology, but not really any more complicated to use than LM317.
post #4 of 19
The TL431 has pretty limited output capability unless it's driving a pass transistor - which is at least twice as complex as an lm317

Linear Tech's LT1084 is iirc pin compatible and better, and cost about $8. These are lower-dropout, allegedly faster, and much higher power output.

There's also the lm338, which is mostly much higher power output plus has features to limit the impact of high inrush currents.
post #5 of 19
lt1084 best ic regulator i ve used.it has high current output(up to 7A) and very simple .in the other hand too expensive
post #6 of 19
LT1963



Quote:
Originally Posted by thedoctor
built in thermal shutdown, built in current sense, built in MOSFET regulator, built in voltage reference, built in Opamp voltage sense and correction, and built in overshoot detect.
that's in fact a super regulator! super similar to the jung super regulator schematics, except a for few differences. but should perform just as well, and those are no bigger than your normal LM317T.

the normal jung super regulator should take at least 1/4 of the EMU0404 board size for a single voltage output. no thank you. i'll take the LT1963 anyday.
post #7 of 19
Quote:
Originally Posted by Eokboy View Post
LT1963

Max voltage is 20v, though.
post #8 of 19
LM338 is a common replacement for LM317 and is functionally equivalent in every respect, except it's rated for up to 3A. Other than that, you might look into Amb's Sigma 11 or Sigma 22 - not sure they'd be cateqorized as simple compared to an LM317/338, though.
post #9 of 19
Quote:
Originally Posted by tomb View Post
LM338 is a common replacement for LM317 and is functionally equivalent in every respect, except it's rated for up to 3A.
5A continuous / 7A peak.

It also has some other nice current regulatory features:

"A unique feature of the LM138 family is time-dependent current limiting. The current limit circuitry allows peak currents of up to 12A to be drawn from the regulator for short periods of time. This allows the LM138 to be used with heavy transient loads and speeds start-up under full-load conditions. Under sustained loading conditions, the current limit decreases to a safe value protecting the regulator."

It's not completely un-blow-up-able, but it's real close.
post #10 of 19
Ya got me there - I hadn't checked the current rating in awhile, but thought it was 3A, for some reason.
post #11 of 19
Quote:
Originally Posted by tomb View Post
Ya got me there - I hadn't checked the current rating in awhile, but thought it was 3A, for some reason.
That's the LM350
post #12 of 19
Here's a question for you guys. What's a better alternative (discrete or IC) to LM337 (the negative version of LM317)?
post #13 of 19
The LM317.

The only reason to use a negative regulator is if you have a non-isolated negative supply voltage. If the supply floats, such as when you have a dual secondary transformer, you can just use two positive regulators to get a dual supply. It works better, and it's simpler.
post #14 of 19
Quote:
Originally Posted by tangent View Post
If the supply floats, such as when you have a dual secondary transformer, you can just use two positive regulators to get a dual supply. It works better, and it's simpler.
Can you explain how you do this and why it's better? This is a new one to me
post #15 of 19
Thread Starter 
LT1963 looks really good. Yep, thats more or less what I searched for
Max 20 volts - well, doesnt matter that much. Should be enough for smaller amps, and for more serious amps you will probably use a dual power supply anyway. and 40V should be more than enough.
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