# How to obtain a 2V precision reference power supply?

Hi, amazing people!
I use PCF8591 to measure the voltage signal in the range of 0-2V, and the reference voltage is 2V, but I can’t find a 2V precision voltage regulator. Most of the chips, such as LM317, LM723 and so on, that can be found to stabilize to 2V are ordinary voltage regulator chips and the precision voltage regulator sources that can be found, such as TL431, are not stable to 2V.
I would like to ask what chip can provide a precision reference voltage of 2V.
Good listening!

you can find 2.048-V precision voltage regulators. would that be OK to not be exactly at 2V (there will be loss of precision in the ADC anyway)?

https://www.mouser.fr/Semiconductors/Power-Management-ICs/Voltage-References/_/N-10vu2?P=1z0w2zw

Don’t forget you can use voltage dividers, so you can measure say 20v with a1.1volt reference .

Here is the problem with your question. Unless you have a recently calibrated precision voltmeter, you will never know what the voltage actually happens to be.
Paul

Maxim makes a 2.048 volt 1% reference. But as Paul_KD7HB mentioned you will have to trust Maxim (or whomever you choose) for absolute accuracy.
The AD584 is even more precise but the lowest voltage is 2.5V. If you divide that down, then you run into the precision of your resistors.

I realize "precision" is something many folks strive for but unless you have a specific application requiring exacting measurement, everything is relative. I find stability more important that absolute precision.

Why not use the 15-bit ADS1115 with built-in 2.048volt reference instead of that 8-bit chip.
Leo..

I agree with @Wawa.

I wasn't familiar with the PCF8591. Now that I look at it, provided only an 8 bit conversion. Which means your measurement steps are 7.8mv** each. Not worthy of an super precise voltage reference. Kinda like putting racing tires on a Yugo.

** 2.0 / 256 = 0.0078125 volts / step aka volts per bit