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Precision voltage references...?

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Conrad Hoffman:
Apparently it's still quite subject to PCB stress; I wonder if you could mount it on a few fine wires and eliminate that? At least that was the claim over in the metrology forum. It's way cheaper than the LTZ1000!

iMo:
Sure, make a slot 7x7mm into the pcb (package is 5x5mm), put the package in and wire it with 3 (or 4) thin wires..
Still it is 5ppm/K max, not comparable with LTZ nor LM399..

--- Code: ---Hermetic 5mm × 5mm LCC Leadless Chip Carrier Package:
Insensitive to Humidity
Thermal Hysteresis: 8ppm (0°C to 70°C)
Thermal Hysteresis: 12ppm (–40°C to 85°C)
Low Drift: 5ppm/°C Max
High Accuracy: ±0.10% Max
Low Noise: <1ppm Peak-to-Peak (0.1Hz to 10Hz)
Low Long Term Drift
12ppm at 1000Hr
18ppm at 3000Hr
--- End code ---

jbb:

--- Quote from: Conrad Hoffman on February 03, 2020, 09:58:22 pm ---Apparently it's still quite subject to PCB stress; I wonder if you could mount it on a few fine wires and eliminate that? At least that was the claim over in the metrology forum. It's way cheaper than the LTZ1000!

--- End quote ---

Maybe a flex PCB with some cunning slits.  You could even add an NTC or RTD next to it, and make a little flex lead pod to sit inside a tiny DIY oven...

Andreas:

--- Quote from: imo on February 03, 2020, 08:47:31 pm ---In LT1027LS8 DS (2016) they spent entire page 10 with the elaboration of humidity influence via PCB stress :)

--- End quote ---

3 slots, 4 slots
The sad truth is that 1 slot is better than 4.


--- Quote from: imo on February 03, 2020, 10:02:46 pm ---Sure, make a slot 7x7mm into the pcb (package is 5x5mm), put the package in and wire it with 3 (or 4) thin wires..
Still it is 5ppm/K max, not comparable with LTZ nor LM399..

--- End quote ---

The T.C. isnt that bad (at least near room temperature).
But the hysteresis in the LS8-package is larger than in the DIP8 package.
So they messed up something with the die attach.

I am wondering if the (obsolete) metal can package shows that large hysteresis.

With best regards

Andreas


iMo:
The LT1027 metal can H package - LT databook '92:
Hysteresis delta 25C  typ 10ppm
Long term stability    typ  20ppm/month

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