Improving the LM3x7 regulator circuit

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Elso Kwak

Elso Kwak

Banned
Joined 2001
geocities.com/elsokwak/
Re: Colonel Mustard in the library with a lead pipe.

Fred Dieckmann said:
"Fred, Any clue which regulator you are eyeballing?"

Yes I am pretty sure I know what they are...... I did have to order them after all. A clue heh ?

"What speaks with one voice, yet walks on four feet in the morning, two feet at noon and three feet in the evening?" Wait a minute, that's not it!


Alright, alright ............. It has more legs than a cow but fewer legs than a spider.
Click to expand...
Hi Fred,
Let's see, a cow has four legs and a spider eight if I am not mistaken.
So your eyeballed reguator has >4 and <8 legs leaving 5, 6, or 7 possible legs. My best guess is 5 legs (SOT23-5). I already tried them and ..............
:clown:
 

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F

Fred Dieckmann

diyAudio Retiree
Joined 2002
Nope.........

Small package voltage regulators usually have higher output impedances than something like a TO220 since they don't have good enough power dissapation and usually a smaller pass transistor.

Now there are some 5 legged TO220 package (like those used on some of the chip amps) regulators like the following:
LT 1185
LT 1067
LT 1528
LT1529
LT 1129
LT1087
LT1085
LT 1185

And even 7 legs like the LT1058.

Of course it may not be any of these part numbers and something completely different
 

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Elso Kwak

Elso Kwak

Banned
Joined 2001
geocities.com/elsokwak/
Re: Nope.........

Fred Dieckmann said:
Small package voltage regulators usually have higher output impedances than something like a TO220 since they don't have good enough power dissapation and usually a smaller pass transistor.

Now there are some 5 legged TO220 package (like those used on some of the chip amps) regulators like the following:
LT 1185
LT 1067
LT 1528
LT1529
LT 1129
LT1087
LT1085
LT 1185

And even 7 legs like the LT1058.

Of course it may not be any of these part numbers and something completely different
Click to expand...

Fred I hope these (I mean the regulators your are targetting) are not a monstrosity as that picture by Dika Wolf......Did I say we need low output impedance???
 
Elso Kwak

Elso Kwak

Banned
Joined 2001
geocities.com/elsokwak/
Re: Nope.........

Fred Dieckmann said:
Small package voltage regulators usually have higher output impedances than something like a TO220 since they don't have good enough power dissapation and usually a smaller pass transistor.

Now there are some 5 legged TO220 package (like those used on some of the chip amps) regulators like the following:
LT 1185
LT 1067
LT 1528
LT1529
LT 1129
LT1087
LT1085
LT 1185

And even 7 legs like the LT1058.

Of course it may not be any of these part numbers and something completely different
Click to expand...

Hi Fred,
Your listing is quite funny as you mention the LT1185 twice.
Also the LT1067 and LT1058 are not regulators, and the LT1087 is obsolete.
Even more funny is this quote from the LT1185 datasheet: (yes I read these, even spell them)
"The LT1185 has a collector output NPN pass transistor,
which makes the open-loop output impedance much
higher than an emitter follower."

How about the low noise LT1764?

;)
 
J

jcarr

Member
Joined 2002
lyraconnoisseur.com/
I imagine that the following query will depart from the scope of this thread so far, but has anyone tried 5-pin adjustable monolithic voltage regulators such as National Semiconductor's LM2941 (positive) and LM2991 (negative), or Linear Technology's LT1129 (positive) and LT1185 (negative)? (The SGS Thomson L200 appears to not have any negative complementary device.) Do these 5-pin devices provide real-world measured or subjective benefits beyond the more common 3-pin monolithic regulators?

And to be more cheeky, has anyone compared the measurements and/or sound of the National Semis against the Linear Techs?

Comments, insights or subjective impressions all welcome.

Bonus: interesting power supply circuit - "Active preloading provides current sinking capability"

http://www.reed-electronics.com/ednmag/archives/1997/010297/01di_02.htm

regards, jonathan carr
 
lgreen

lgreen

Member
Joined 2003
Regulators

Ive use the LT1964 and LT1962 as regulators.
They worked very very well.
I could barely see the noise on my scope's highest setting.

(More info here)

Here is the circuit:

An externally hosted image should be here but it was not working when we last tested it.


Here is the single sided board I made (bottom view).
All hand soldered.
That is a dime, you see the devices are very tiny.

An externally hosted image should be here but it was not working when we last tested it.
 
H

Htguy

Member
Joined 2003
TI TL783 a good option...

Hi,

After spending many hours online looking at data sheets, it looks to me that the Texas Instruments TL783 3terminal reg is a pretty good option.

-zener vref (lower noise than bandgap ref)
-line reg ~1-2us
-load reg ~20us



Any thoughts one else have thoughts on this?

God bless...

Mark
 
M

Michael Mik

Member
Joined 2005
Improving LM3x7

Hi Fred,
luckily I found the thread about that subject and saw your worthy contribution, but somehow I get lost over several threads. Your post #34, is that the last word on this subject?
Can it be applied to the 3A and 5A LM-type also?
What, in your words, will be the exact improvements?
In all data sheet are shown the tracking preregulator. What excactly will happen there, and will that improve the LM3xx?

Since I could not write you an email, I hope you answer here, if you are not to tired to this endless discussion pro and con.
Thanks
Michael
 
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