[volt-nuts] Voltage Reference.

Andreas Jahn Andreas_-_Jahn at t-online.de
Sat Nov 1 04:34:52 EDT 2014

Hello Dan,

If you look for sub-ppm then also noise or hysteresis might be a issue.
Nearly all good references have around 0.6ppm low frequency noise with 
respect to output voltage.
(giving 3uVpp for 5V).

I have tested 2 VRE3050A for noise and one for TC.
In the range of 16-40 deg C average tempco was low (about 8 ppm over 
16-40 deg)
(nearly zero around 28 deg C)
but hysteresis at 25 deg was 4 ppm and 0.1-10 Hz noise around 9uVpp.
The second VRE I have only tested for noise which gave also around 9 uVpp.
I do not know if both devices are "mondays" devices since I bought them 
at a time shortly after Thaler was sold to APEX.
And current consumption was far below the value of the datasheet.
But for me I decided that they are no good value for money for my needs.

For the same money you get 5 AD586LQ with <3uVpp noise and nearly no 
hysteresis in the above temperature range.
Ok perhaps you have to select them for tempco. In my case tempco is 
compensated by a microcontroller with a (NTC) temperature sensor.

The ADR4550 suffers like nearly all plastic housings from large 
hysteresis and perhaps from humidity sensitivity.
I measured a nearly linear average tempco of -2ppm/K on one sample. 
Hysteresis around 16ppm at 25 deg C.
Noise was around 3uVpp like good buried zener devices.

The LM399 that I have tested are far better in T.C. than the 1ppm/K that 
are stated in the datasheet.
At least this is true around room temperature (10-40 deg C).
Only noise is rather different from device to device.
Some around the 0.6 ppm others are a factor of 2 or so larger in noise.
So perhaps you will have to select for noise.

Some Info of other features of LM399 (tilting drift, termal isolation) 
can be found here:

If you need low T.C. and low noise there is nearly no way not to use the 

With best regards


Am 31.10.2014 um 20:09 schrieb Dan Kemppainen:
> Hi All,
> I'm working on something that requires a stable voltage reference.
> Long term stability isn't needed, but good thermal stability is. In
> other words it would be nice to have sub ppm/C temperature, but a few
> ppm/month or even per day isn't an issue.
> Anyway, it got me thinking about building a reference for fun, with some
> of the newer IC's available, but doing so in an ovenized housing.
> I know the LM399's and LTZ1000's are out there, but has anyone looked at
> any of the newer IC's out there?
> For example this one seems to have pretty good ppm/C drift:
> http://www.digikey.com/product-detail/en/VRE3025JS/598-1916-ND/2036526
> However it's not cheap.
> And this one looks pretty good for the sub $10 price.
> http://www.digikey.com/product-detail/en/ADR4550BRZ/ADR4550BRZ-ND/3196874
> This is the one I was thinking about parking in an oven. It has a
> turnover around 70C.
> Has anyone played with inexpensive reference chips, and tried to make a
> good reference out of them? Any thoughts or comments welcome!
> Dan
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