I am using AD7682 as an ADC and using its external voltage reference mode.
The external voltage reference is buffered by AD4841-2 dual OpAmp.
I power the AD4841 with +- 5.040V power supply. The voltage reference is +5.006V.
However, after buffered by AD4841, the +5.006V reference only becomes +4.386V.
It seems that AD4841 is not rail-to-rail,
Could anyone help on this?
The problem is that you are exceeding the input voltage range of the ADA4841-2, which is on a +5V supply is -0.1V to 4V. If you want to use the ADA4841-2 to buffer the reference you’ll need to increase the power supply to at least 1V above the reference voltage.
I hope this helps.