Re: 0.1 Volts output voltage regulator

On Thu, 15 May 2008 13:54:38 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

Winfield Hill wrote:
On May 14, 2:42 pm, Tom Bruhns <k7...@xxxxxxx> wrote:
On May 14, 11:13 am, john <conphil...@xxxxxxxxxxx> wrote:

I am looking for a +/- 0.1 volts output voltage regulator. I have
+/- 5 volts input. Any advice!
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

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.


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 :-)))

Ever hear of a negative supply rail ?:-)

...Jim Thompson
--
| 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 |
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