Voltage Reference off spec or normal?

Thread Starter


Joined Jul 9, 2015
I needed a 2.5V reference voltage and i bought a LM4040BIZ-2.5.It is 2.5V ±0.2% shunt regulator but when i connect it with a series resistor i'm reading about 2.47 volts no mater what load current i set (up to 15mA). Is this within spec or am i doing something wrong?


Joined Feb 24, 2006
Let's see.

\(\frac{.030}{2.5}\;=\;0.012 \;= \;1.2%\)

Seems like it is out tolerance. When was your meter last calibrated? You do calibrate your instruments at least once a year per ISO-9001 -- right? Did you get the little sticker from the independent lab that did the calibration?


Joined Feb 24, 2006
So which one do you believe? Are you going to get the first meter professionally calibrated? Is that first meter just a throwaway cheapie that probably can't be calibrated anyway?

\(2.5 \times 0.002 = 2.505\)

\(2.503 \le 2.505\)

Looks like a winner, and you have a new voltage reference to check meters with.