[volt-nuts] volt-nuts Digest, Vol 55, Issue 23

Andreas Jahn Andreas_-_Jahn at t-online.de
Sat Mar 29 13:07:24 EDT 2014


Hello,

I do not know how you measure the "noise".
If its 0.1-10Hz peak-peak noise a value of 10uVpp is rather high.
Typical noise should be around 4.2uVpp (0.6ppm peak peak) for a zener 
with around 1mA current.
The LM399 that I have measured range from below 3uVpp to around 7uVpp.

Perhaps you should do some thermal isolation around the LM399.
Additional use a 100nF decoupling capacitor at Input (heater) and output 
(zener).

By the way: there are 2 threads on the eevblog regarding LM399 + LTZ1000

http://www.eevblog.com/forum/projects/lm399-based-10-v-reference/
http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/

With best regards

Andreas




Am 29.03.2014 15:57, schrieb Jan Fredriksson:
> Yes, LM399 good good! Me like!
>
> The dozen LM399 have now spent a day at an average 0.0uV deviation, +/-0.2u
> peak to peak probably below 0.1ppm rms (10s averaged), despite the room
> temperature changing by something like 5 degrees (C). Condition; Bench
> supply 12V, 12 IC paralleled, current limited by 2K7 to each IC, output via
> 2K7 from each.
>
> I got my LM399 from ebay at $4.99 each. Seller polida2008. (I'm in no way
> associated with the seller). Buying ICs on Ebay is risky but these where
> good.
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