Electrical Engineering - <1VDC Regulator

Author

<1VDC Regulator

hsuabraham@gmail.com

2008-02-10, 1:25 pm

All,

I need some help designing a <1VDC regulator (ideally, 0.1VDC minimum)
and I haven't been too successful. I found the following article:
http://www.powermanagementdesignlin...owto/164300442.

But when I simulated it in Circuitmaker 2000 with an adjustable
regulator (LM317), I wasn't able to get the <1VDC results as shown.
Has anyone verified the results from the article above? Or have any
other ideas on how to get <1VDC?

Thanks,

Abe

Tim Perry

2008-02-10, 1:25 pm

<hsuabraham@gmail.com> wrote in message
news:fb474c17-dc5e-4582-a08e-db5c1762c89a@i29g2000prf.googlegroups.com...
> All,
>
> I need some help designing a <1VDC regulator (ideally, 0.1VDC minimum)
> and I haven't been too successful. I found the following article:
> http://www.powermanagementdesignlin...owto/164300442.
>
> But when I simulated it in Circuitmaker 2000 with an adjustable
> regulator (LM317), I wasn't able to get the <1VDC results as shown.
> Has anyone verified the results from the article above? Or have any
> other ideas on how to get <1VDC?
>
> Thanks,
>
> Abe

The trick to getting a 0 to whatever voltage using a 317 is to have a
negative voltage supply that serves as a reference point to the regulator in
addition to the positive supply.
I have used a couple for this, one fixed for the negative reference and the
variable one driving pass transistors.

A cheaper trick is to simply add diodes (or a zener) to the ouput of the 317
(but it wont help is you are driving pass transistors for a high current
output).

Palindrome

2008-02-10, 1:25 pm

hsuabraham@gmail.com wrote:
> All,
>
> I need some help designing a <1VDC regulator (ideally, 0.1VDC minimum)
> and I haven't been too successful. I found the following article:
> http://www.powermanagementdesignlin...owto/164300442.
>
> But when I simulated it in Circuitmaker 2000 with an adjustable
> regulator (LM317), I wasn't able to get the <1VDC results as shown.
> Has anyone verified the results from the article above? Or have any
> other ideas on how to get <1VDC?
>
It works.
I used that technique to produce a 0 to 100V DC 0 to 10A power supply,
adjustable in steps of 10mV and current limit in steps of 10mA as my
first degree project, more years ago than I would care to mention...

I suspect that you are getting your common references mixed up..

Try this: Model a standard dual (positive and negative rails) regulated
supply. Say +15v, -5v. Now add an additional adjustable positive
regulator that takes the +15v as input but uses the -5v rail as the
common reference. Set its voltage to +5.1v wrt its reference, the -5v
rail. You then have a +0.1v regulated supply, using the output of the
adjustable regulator wrt the common reference of the +15v regulator..

--
Sue

hsuabraham@gmail.com

2008-02-10, 1:25 pm

Thanks Time and Sue,

I understand what you guys are saying. Now, I can definitely simulate
and get the <1VDC now with a negative voltage reference. (That 0-100V,
10A adjustable regulator is pretty cool.)

But the thing I still don't understand is that the article seems to
insinuate that one can use only positive voltage supply references. Is
this not true then?

Thanks,

Abe

On Feb 10, 12:59 pm, Palindrome <m...@privacy.net> wrote:
> hsuabra...@gmail.com wrote:
>
>
>
> It works.
> I used that technique to produce a 0 to 100V DC 0 to 10A power supply,
> adjustable in steps of 10mV and current limit in steps of 10mA as my
> first degree project, more years ago than I would care to mention...
>
> I suspect that you are getting your common references mixed up..
>
> Try this: Model a standard dual (positive and negative rails) regulated
> supply. Say +15v, -5v. Now add an additional adjustable positive
> regulator that takes the +15v as input but uses the -5v rail as the
> common reference. Set its voltage to +5.1v wrt its reference, the -5v
> rail. You then have a +0.1v regulated supply, using the output of the
> adjustable regulator wrt the common reference of the +15v regulator..
>
> --
> Sue

Palindrome

2008-02-10, 5:25 pm

hsuabraham@gmail.com wrote:
> Thanks Time and Sue,
>
> I understand what you guys are saying. Now, I can definitely simulate
> and get the <1VDC now with a negative voltage reference. (That 0-100V,
> 10A adjustable regulator is pretty cool.)
>
> But the thing I still don't understand is that the article seems to
> insinuate that one can use only positive voltage supply references. Is
> this not true then?
>
I couldn't find where in the article you read that. However, an offset
zero reference works, irrespective of whether the offset is negative
(for a positive output supply) or positive (for a negative output
supply. Where one has a dual regulator, producing both positive and
negative output voltages, the offset reference is automatically included
"at no extra cost".

Another neat little trick is to use a high power bridge operational
amplifier (or even some audio amplifiers) - these can be used to produce
a dual output power supply where each output can be varied over a wide
range of both positive and negative output voltages, plus achieve
tracking "at no extra cost"..

--
Sue

Tim Perry

2008-02-10, 5:25 pm

"Palindrome" <me9@privacy.net> wrote in message
news:QeIrj.113686$9w2.53893@fe12.news.easynews.com...
> hsuabraham@gmail.com wrote:
> I couldn't find where in the article you read that. However, an offset
> zero reference works, irrespective of whether the offset is negative
> (for a positive output supply) or positive (for a negative output
> supply. Where one has a dual regulator, producing both positive and
> negative output voltages, the offset reference is automatically included
> "at no extra cost".
>
> Another neat little trick is to use a high power bridge operational
> amplifier (or even some audio amplifiers) - these can be used to produce
> a dual output power supply where each output can be varied over a wide
> range of both positive and negative output voltages, plus achieve
> tracking "at no extra cost"..
>
> --
> Sue

I have heard of using a Crown DC series amps to charge car batteries in a
pinch by applying a small battery voltage to the input.

Michael A. Terrell

2008-02-11, 1:25 pm

Tim Perry wrote:
>
> I have heard of using a Crown DC series amps to charge car batteries in a
> pinch by applying a small battery voltage to the input.

I jump started a car once by rolling my bumper to the other car's
bumper, and used a six foot scrap of solid aluminum clothesline wire
between the positive terminals. Luckily, it started the first try. The
wire was too hot to hold onto after that.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

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