Hi:
I need to implement a buffer for VcomDA of a codec, and i only have OPA227 or OPA1642...
The VComDA is 2.5V DC voltage as i'm using 5V supply... for making the circuit simple, i want the opamp to be supplied by sigle supply of 5V.
Reading the datasheet of OPA1642, i found that the common mode voltage range would be from -0.1 to 1.5 V ( (v-)-0,1 to (v+)-3.5)...
But i don't fully understand what does it means... I would suppose that the common mode voltage should not exceed that range... so if im using a simple voltage follower, with negative realimentation of the output... both inputs should have 2,5V, what gives me 2.5Vcm, and i could not use this opamp... Is all this right?
But now, taking the OPA227, the common mode voltage range is from 2V to 3V ((v-)+2 to (v+)-2)... so i could use it as my common mode voltage is always of 2.5V...
So... if all of this is right... i should be able to use the opa227 with a dc positive input of 2,5V... with output realimentation to negative input, and at the output i would get the desired 2.5V steady... Am i right?
i need to buffer this dc voltage cause it is the reference to many other line drivers, so in the data conversion forum they told me to use an opamp to buffer it with a simple voltage follower
