Confused Noob(ish) Needs Info On Voltage Refs

[Thomo]

I am looking to build some opamp based voltage regulators, probably based on the Sulzer regulator. I would go for something a little more complex, but size is very important, I really want this reg to be able to mount them directly on the pcb's of my cd player etc.

What has confused me is that most people use the LM329 as a voltage reference. Is this absolutely the best/lowest noise reference there is?

I have searched and read, but really don't know enough about what I am reading in datasheets to fully understand.

Please help guys, I am always willing to learn.

Lee.

[Conrad Hoffman]

There are a boatload of references and sometimes it's hard to choose between them. Series or shunt? Buried zener or bandgap? Tradeoffs between line and load regulation. Noise- high frequency hash can be filtered out, but low frequency instability is nearly impossible. Temperature stability. IMO, if you were building a calibration source for your test equipment, you'd look for very different things than for an audio regulator reference. If it moves a dozen or more ppm/degree, you probably don't care. If you aren't going to trim it, initial accuracy might be important. I prefer trims, and tend to want odd voltages, so things like the TL431 appeal to me. I've also been known to use good old fashioned zener diodes and a current source or in a "wrap around" opamp circuit. Look at the offerings from Linear Technology, National, and Maxim. For some really unusual stuff, check out Thaler. Ultimately, you probably can't make a bad choice, since you're going to buffer it. The LM329 is nowhere near the "best" reference out there, but there may be no useful advantage in using something better if you apply it properly.

[Thomo]

Oops, I didn't realise I'd had a reply.

Many thanks for the informative reply. I have built a couple of regs now, using proven and well-documented lm329 refs.

I have received a couple of samples from Maxim, and will have a go with those when I get a bit more time. Unfortunately I don't have a scope to test for noise or anything like that. For test equipment I rely on my ears, which seems the best way to me.

Regards, Lee.

[keantoken]

There's also the Jung regulator, which is supposed to work unimaginably well. It is a revamped version of the Sulzer. If you don't already know about it, Google is your friend.

- keantoken

[peranders]

Just wondering Thomo, why don't you use the regulators that you sell?

Quoting you:

By replacing them with SPower regulators, you are effectively allowing the circuit to work much closer to its full potential. You can expect far more musical detail, with a lower noise-floor and greater spaciality within the soundstage.

[Thomo]

Originally posted by peranders
Just wondering Thomo, why don't you use the regulators that you sell?

Quoting you:

Hehe. Simple answer:

I am broke and cannot afford them. Unfortunately I don't make them, & only make a little profit on them. Hopefully business will pick up much more when I am able to buy in more stock to sell (still waiting for my startup funding).

The regs I am building are pretty similar to the Sulzer circuit. They're not as good as the SPower, and as soon as I can afford it, I will probably upgrade some of them. Also, I enjoy the diy aspect.

Lee.