0.1 Volts output voltage regulator

LM317

Wait a sec.. I think I was too quick. It doesn't fully pinch off now that I think about it.

Voltage dividers and op-amp buffers will do it, conceptually anyway, but the details depend on the load characteristics. Best regards, Spehro Pefhany

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You didn't mention what sort of accuracy and regulation you need, nor what the load current is (static and dynamic). If you use a linear regulator, the efficiency will be awful: 100%*0.1/5 = 2%, maximum. But if your load current is low, that may not be an issue. In fact, if the load current is low, just use a dual op amp, one side connected as a unity gain follower and the other as a unity gain inverter, driven from the follower output. You may be able to do OK with just a resistive divider from your 5V to generate the 0.1V to put into the follower. For higher load current, consider an LT3080 for the positive side. If what you want is really a voltage reference, use a precision 1.24V reference, or the like, and divide that down and buffer it with a low-drift (and perhaps low offset) op amp follower.

Cheers, Tom

It will regulate down to (or below!) zero volts if you set the adjust pin right. Ditto LM337.

The op left a lot unspecified, as usual.

John

Hi,

The output current is 0.1A. Regards, John

"john"

** You can use LM317s and LM337s with each adjust terminal referenced to the opposite 5 volt rail.

..... Phil

So a 1% shift in either 5V line changes the opposite 0.1V output voltage by 50% wrt ground?

Best regards, Spehro Pefhany

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speff@interlog.com             Info for manufacturers: http://www.trexon.com
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"Spehro Pefhany" "Phil Allison"

** The OP stated he had +/- 5 volt rails - so who am I to doubt him ......

Plus - I only posted an idea he CAN use if he likes.

BTW:

The regulation of 7805 / 7905 type ICs is way better than 1% under near constant load conditions, as is the case with the majority of circuits.

Setting up precise +/- 1.05 volt refs for 317 / 337s perfectly possible too.

.... Phil

One way would be to use an opamp plus pnp/npn followers at the output to get to your 100mA. Use the whole thing as a follower. A positive and a negative reference set, say, +/-1.24 volts. You can use two TLV431. Or if it has to be really cheap take the TL431 at +/-2.5V. Divide that down to +/-0.1V via resistors and, voila, there is your regulator.

Add overload protection if needed.

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Regards, Joerg

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The LT3080 is definitely the way to go, for +0.1 volt out. It's adjustable down to zero (0.0) volts. What's not to like? Well, OK, there is a required minimum load current of 500uA max, to operate the circuit.

Thanks for the post, Win. The setup of my googlegroups "kill all but good guys" has been validated. Not seeing you post in a while had me concerned that I had a defect in my "good guys" file.

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Hmm, why don't you just filter the domain of the poster like I do? Dumps most Google spam but not Win's post.

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Regards, Joerg

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But John won't get his negative range then. Plus it's an LDO which I won't trust nomore never no more. AFAIU he wants it adjustable between

-100mV and +100mV. I'd just do the usual ref-opamp-pnp/npn thing.

Just to be a nitpicker here, I wonder how one would ascertain a 500uA load current at 0.0V :-)))

--
Regards, Joerg

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Use another domain or send PM.

Given the roving-origination spammers it's easier for me to FLAG "good guys", but otherwise kill googlegroups... I find so many forged headers, that posting host is usually the only valid one.

My filtering is working really well. Unfortunately my filter files don't work with many servers due to lack of headers... the Forte, Inc. (Agent) server ($2.95/mo) delivers most headers, but news.west.cox.net does not, so many people have reported back to me with problems.

I _have_ noticed, as others have also reported, spam is down from googlegroups, but rose up elsewhere ;-(

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave

Ever hear of a negative supply rail ?:-)

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave

Can be done. Who knows, then the neg rail comes before the pos rail ... phsst ... BANG.

--
Regards, Joerg

http://www.analogconsultants.com/

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You have way too much "phsst ... BANG" in your life ;-)

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave

It's more on the BANG side by now ;-)

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Regards, Joerg

http://www.analogconsultants.com/

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