Electronics > Metrology
ADR1399 reference
bobAk:
Hello. Has anyone tried to connect adr1399 in series? Like lm399. It’s more interesting how it behaves, since changes in the control loop of the shunt part in comparison with lm399 led to the need to install ~1 µF 5 ohms. In theory, there should be no problems, due to low impedance. Requires ~14 volts with low noise.
misterpulcri:
Hello,
Apologies, my question is pretty basic but I see a lot of expertise here and no other suitable ADR1366 forum. Happy to be redirected somewhere more appropriate if I am in the wrong place.
I have attempted to build a basic voltage reference using a ADR1399K with +12v supply, 1K3 shunt for 3mA at 12V, 5R1 and 1uF as per the datasheet. Have built this three times now on breadboard and stripboard. Each iteration produces 6.920V instead of the expected 7.05V. At each power on my DVM reads 6.925 and within a few seconds this decreases and stabilises at 6.920V. I have verified that I have just over 3mA flowing through the shunt. Have checked with 2 other hand held DVMs and get the result as my bench DVM. Have checked DVMs against a fairly accurate voltage source
Am I missing something or is my ADR1399 faulty?
Thanks
Sean
Kleinstein:
There is quite some variations between different units of LM399 and ADR1399. The ref. voltage can vary quite a bit. The specs are 6.75 to 7.3 V, though the extreme values are rare. 7.05 V is just a typical value. So the 6.92 V are perfectly reasonable.
misterpulcri:
Ah, OK thanks. I can at least stop pulling my hair out.
Andreas:
--- Quote from: misterpulcri on July 10, 2024, 04:29:17 pm --- At each power on my DVM reads 6.925 and within a few seconds this decreases and stabilises at 6.920V.
--- End quote ---
Hmm,
Are you Kelvin sensing the voltage at the zener or are you measuring the sum of the zener voltage and the voltage drop of the heater current on the ground connection?
But even without that it needs some time until steady state is reached.
with best regards
Andreas
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