Electronics > Projects, Designs, and Technical Stuff
Precision voltage references...?
Conrad Hoffman:
My calculator must be broken because it says I wrote the Mini-Metrology articles 24 years ago. Hard to believe. Anyway, the reference used the LT1027 in the metal can. I just tonight measured the original unit against a good standard. It was originally measured by a local cal lab and tagged at 9.999948 VDC. 24 years later it measures 10.000125 VDC. Maybe the chip drifted. Maybe the inexpensive metal film resistors drifted, but IMO, that's not bad. I have a second one built around the same time and it was tagged at 10 VDC even. It now measures 10.000334 so also not too terrible at 2+ decades. Interesting that both went up, or maybe chance?
iMo:
All those LT10xx, LT12xx, AD5xx, REFxx were developed for 12-14bit ADC/DAC apps many decades back. Provided you do with 5V your +334uV off is still <1LSB with 14bit.
PS: I would add LM399 to the list too..
magic:
--- Quote from: Conrad Hoffman on February 03, 2020, 09:52:27 pm ---Unfortunately, the LT1027 hasn't been made in a metal package for years. That one was really great for the money.
--- End quote ---
Did anyone try mounting the SO8 version inside a TO39 can and soldering it shut?
Conrad Hoffman:
--- Quote from: imo on February 04, 2020, 09:40:24 am ---All those LT10xx, LT12xx, AD5xx, REFxx were developed for 12-14bit ADC/DAC apps many decades back. Provided you do with 5V your +334uV off is still <1LSB with 14bit.
PS: I would add LM399 to the list too..
--- End quote ---
True, but the numbers are for 10V, as the reference has a 2X buffer built in and nothing in the circuit is adjustable. OTOH, tech doesn't usually stand still for 24 years and today we want references for 18 bit systems or more. Best reference 24 years ago- LTZ1000. Best reference today? LTZ1000! Maybe we've hit the wall.
iMo:
Ok, thus with 10V you are still <1LSB with 13bit ADC/DAC :)
Anyhow, all those references I listed above were not designed for something like >5 digits, imho. We use them as they are cheap and easy to apply.
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