Power supply/voltage regulator

[bjbdts]

Hi, all
I am trying to find a DC power supply/voltage regulator with high accuracy, for example for 0-10V range, the accuracy need to be several mV. I know one company bk precision with the required accuracy (about 8mV), but I really don't want the "horns and whistles", and want to get the subcomponent. I contacted the company, but didn't have any luck. Does any of you guys have information on this?
Thanks.

 

[itsmoked]

You have give so so so so so so little information I cannot.

I don't know if you are referring to bench supply, or an embedded supply or an IC regulator? Please provide more info.

What is it running?

 

[IRstuff]

How much current, etc.?

There are bandgap references that can be used as the core of a power supply.

TTFN

 

[bjbdts]

The current should be about 50mA or less. I am trying to find a voltage regulator for a VCO. Right now I am using a precision potentiometer to do the job.
My ultimate goal is to find the embedded supply or IC regulator, but at this stage bench supply is acceptable.

 

[itsmoked]

More questions.

Does this need to be variable? If so from what to what?

Is it powering the VCO or just controlling it?

 

[IRstuff]

So, you should be able to use a bandgap reference followed by a unity gain buffer?

TTFN

 

[VEBill]

Or, use the normal Phase Lock Loop (PLL) circuit to control the VCO based on the digitally-selected frequency. This is, by far, the most common application for VCOs.

 

[OperaHouse]

Go to eBay and look in Calibrators & Standards section. There is a guy there selling a bare circuit board for a 10V calibration standard for less than $6, fully calibrated for $45. Doesn't sound like you need it calibrated so you may be able to get one wired and tested for in between that. Add an op amp for adjustment and higher current.

 

[bjbdts]

Hi, itsmoked
Yeah, it needs to be variable, from 0-10V.
It will be used to control the VCO.

 

[itsmoked]

bjbdts;

Check these out they look like a match.
Nice price, low ripple, nice regulation too.

http://www.web-tronics.com/30serdigrobe.html

 

[IRstuff]

So, you could simply hook up a pot to a buffer amp to bandgap reference:

http://www.national.com/ds/LM/LM4130.pdf

Note that the voltage noise is 150 MICROvolts p-p

TTFN

 

[bjbdts]

itsmoked:
Fabulous! Great website, I found one supply that can actually give me 2.8mV regulation!
Thanks a lot

 

[bjbdts]

TTFN:
I don't quite understand the bandgap references, I guess they are for temperature compensation? I am more concerned about the regulation accuracy. When I need to fine tune the VCO frequency, I need to have a voltage control to change only several mV.

 

[IRstuff]

No, they are used as voltage references.

While the proposed power supply is noisier and less accurate. The power supply link shows ripple at <1 mV, while the bandgap reference has 0.15 mV ripple.

Additionally, the power supply product manual shows a display accuracy to 1%+2 counts, while the bandgap reference can be accurate to 0.05% initially and accurate to 0.65% over a much wider temperature range. Not clear if the power supply is even specified at temperature. Since the power supply display is only 3 digits to start with, the power supply accuracy is at best 0.3V for a 10V output, while the bandgap reference can be accurate to 0.06V for the same 10V output.

Therefore, the bandgap reference is more stable, more accurate and less noisy.

TTFN

 

[itsmoked]

I agree with all of IRstuffs points adding only that the "proposed power supply" is easy. Not anywhere near as accurate but easy. The OP doesn't sound like he wants to fabricate anything. If he does.... Then yes use a bandgap a pot and a buffer as IR suggests.

 

[bjbdts]

itsmoked:
I contacted the company, The precision is not that high as described in the specification. The terms "line regulation" and "load regulation" are confusing!

 

[itsmoked]

No it isn't!

Line Regulation: How the voltage to the regulator effects the regulators output.

Load Regulation: How the current being drawn from the regulator by its load, effects the regulator's output voltage.

 

[nbucska]

There is something missing: Why do you need accuracy?
why not make a PLL from it ? (i.e. compare the output frequency to the desired one and control the VCO input with the error )

what do you want to use the output fr.?




<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[bjbdts]

The point is that I don't know exactly what's the desired frequency before doing the experiment. The frequency changes with experimental setup. That's why I need to fine tune the VCO to get the desired frequency.

 

[nbucska]

So you don't need a VCO, you need an adjustable frequency
soure.

What is the frequency range and frequency stability you need?

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032