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Old 5th September 2013, 03:52 PM   #11
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I like TL431 as well, a very handy device. Way back when I was making voltage references I concluded that HF noise is of little consequence because you can always filter it out. What was much harder to deal with was LF noise on the order of Hz or less. It wasn't practical to filter it out and it didn't always average to zero over a short time period. Not good for a calibration standard. For audio circuits I'd think only the HF noise is an issue, and this is easier to deal with, meaning there are really no horribly bad choices. PPM DC stability just isn't an issue.
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Old 5th September 2013, 04:02 PM   #12
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I made a series regulator using a 6CG7 as cascode amp and a 6DE7 as series pass, and a 60V neon as reference.
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Old 7th September 2013, 07:28 PM   #13
brayan is offline brayan  Malaysia
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A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "zener knee voltage", "zener voltage" or "avalanche point" from Wiki.

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Old 10th September 2013, 12:39 PM   #14
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I assume an LM329 is better than a simple zener in terms of noise and stability?

I would like to settle down to a small-sized choice. A TO-92 or a simple zener (sized as an ordinary 1N4001 diode) are the best for my layout, that is why I ask.
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Old 10th September 2013, 07:24 PM   #15
KSTR is offline KSTR  Germany
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LM329 reference is an excellent choice for a 12V or 15V regulator.
It will a) center (more or less) the common-mode voltage on the opamp input pins at half-supply (== 1/2 output voltage) and b) allow the reg to be run at low gain with a high feedback factor. And c) it will allow for enough volts accross a constant current source or resistor to feed the reference. All this will help perfomance compared to references that are significantly lower or higher voltage than half the output voltage.

Last edited by KSTR; 10th September 2013 at 07:27 PM.
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Old 10th September 2013, 07:52 PM   #16
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I will need 9V and 16V. I assume that for the 16V it would be perfect, how about the 9V?
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Old 11th September 2013, 11:16 AM   #17
KSTR is offline KSTR  Germany
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If you have a shared design (common GND for 9V and 16V and common input) you could just use a single reference and two opamps all running from the 16V line, one at slightly lesser gain to give 9V instead of 16V.
You could also use TL431's with a bit of filtering instead of LM329. Many options to choose from, depending on what level of circuit perfomance and complexity/parts count you're after.
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Old 11th September 2013, 12:44 PM   #18
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Each supply sill be separate.

I will implement Sulzer regulator, which already has very good performance for my needs. What is a fact though, as I stated above, is room. I need physically small references. LM329 is TO-92 which is good, a zener is also as small as it gets. TL431 is a whole IC as I see, so is ruled out.

As I said before a zener should suffice (the original Sulzer uses that), but why not try something better that fits my tight layout. LM329 is good as far as both performance and size is concerned. But if it is not going to suit me for the 9V supply, I won't use it after all and it's ok. But I think it will, won't it?
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Old 13th September 2013, 09:43 AM   #19
AndrewT is offline AndrewT  Scotland
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tl431 is available as a To92 3pin package and probably in smaller smd as well.
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Old 13th September 2013, 05:44 PM   #20
KSTR is offline KSTR  Germany
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Yep, SMT TL431/432 is available in almost any footprint and pinout, plus it's an industry standard and will probably continue to be available "forever"
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