Electronics > Projects, Designs, and Technical Stuff
Want a 5ppm/C (max) reference? Then don't buy a voltage reference...
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SiliconWizard:
Well, out of curiosity, I just took a look again at the MAX6126 page: https://www.maximintegrated.com/en/products/analog/voltage-references/MAX6126.html
They state "But some versions of the family are Not Recommended for New Designs", which kinda sounds, knowing Maxim, like those versions are going to be discontinued any time now. You make a point. But it has lasted for a few years (I think I selected it like 4 years ago, that's admittedly not much).

Its successor doesn't look bad though: https://www.maximintegrated.com/en/products/analog/voltage-references/MAX6226.html
bob91343:
Initial accuracy of 0.1% isn't good enough.  I need something that is closer, right out of the box, to calibrate my instruments.  Even 0.01% is marginal.

Is there anything reasonable in price that is good enough?  Back in the day you could buy a Weston standard cell and get a pretty good reference but they were expensive.
tggzzz:

--- Quote from: SiliconWizard on July 09, 2019, 03:40:54 pm ---
--- Quote from: tggzzz on July 09, 2019, 03:27:11 pm ---Besides, "friends don't let friends use Maxim".

--- End quote ---

Yeah, this is your opinion though. Maxim makes some pretty good products (I tend to favor Linear/AD for various reasons, but still). I admit they are not always the best with support and availability (especially for their MCUs as far as I'm concerned), but to knock them off altogether... sounds a bit excessive.

--- End quote ---

My introduction to Maxim was for a new interesting specialised device. performance was right, price was right, but there was never any availability. I had the feeling they "ran the device up the flagpole to see who saluted"; no salute => no production.

Only later did I come across "friends don't let friends use Maxim". It resonated with me, i.e. it confirmed my prejudice.
SiliconWizard:
I understand. And now that I've just seen that the reference I used is going deprecated doesn't bode well either... this was only for a few units-project so not a huge issue here, but still. The "successor" I just saw, flagged as "new", looks pretty nice but... it costs almost twice as much!
tggzzz:

--- Quote from: bob91343 on July 09, 2019, 05:44:44 pm ---Initial accuracy of 0.1% isn't good enough.  I need something that is closer, right out of the box, to calibrate my instruments.  Even 0.01% is marginal.

Is there anything reasonable in price that is good enough?  Back in the day you could buy a Weston standard cell and get a pretty good reference but they were expensive.

--- End quote ---

Saturated Weston cells are 40uV/C, i.e. ~40ppm/C. Mine is still in spec after 70 years.

Newer references are based on zener diodes and are unsurprisingly expensive.
One option is to get a well-aged device and get it calibrated by a calibrated HP3458.
Alternatively new 6.5 digit bench multimeters are around £1000.
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