Hello Bob,
the instrument will be your least worries.
with 20-80ppm/K you will need a very well stabilized (<0.1K) temperature
environment for the references.
Otherwise you will not detect ageing but the temperature of your
environment.
A volt nut would only use the LM329 from the list (buried zener).
The others are bandgap references with much larger ageing drift.
But to detect ageing after some 100 hrs you will need a well stabilized
current source (< 0.1% drift during setup)
or a even better voltage source (<0.05% over temperature and ageing) and
a rather stable resistor for each reference in the setup.
If you use sockets for the references their drift will outperform the
reference drift if the board is handled (e.g. for measuring)
so you will need to have a (relay-) multiplexer for your instrument.
If you solder the references to a board you will create stress to the
device and this will give a large initial drift after soldering.
with best regards
Andreas
Am 10.03.2014 01:35, schrieb Bob Albert:
I have a 3456A. Is that good enough?
Bob
On Sunday, March 9, 2014 4:41 PM, Jan Fredriksson <[email protected]> wrote:
I have a batch of voltage references ICs on the shelf, several thousand of
each type. They all have date codes of around 1983, ie 30 years old. It
would be great to have some drift data on them.
The ones listed below are the best of the bunch.
- AS431, TO-92 and SOIC-8, 20ppm/C 120nV/sqrtHz (0.5% or 0.1%?)
- LM385Z, TO-92, 80ppm/C, 600nV/SqrtHz, 60uV, 20ppm/SqrtKhr
- LM329CZ, TO-92, 75nV/sqrtHz, 30ppm/C 7uV noise 20ppm (8ppm?) /SqrtKhr.
- AS2951/2954, SOIC-8, 20ppm/C
I am willing to send a handful (like at least 50 pcs) to anyone who can set
up and monitor the drift of them for a few months and send me some data.
Any takers?
I will do similar monitoring myself, but would appreciate data from others,
that's why I am doing this.
I am also building some other references to compare with, based on LTZ1000
and other zeners.
I am not asking anything in return, except that you return drift data,
measured with some decent method, ie single digit ppm stability.
If you happen to have some resistors rated like 10ppm/C or lower, surface
or hole mount, I'd appreciate some of those in return, in values 1K-10K,
but that is not a requirement.
Jan
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