Hello,
In my design I need to buffer about 45V-48V and about 30V. For this purpose I want to use two Opamps in Unity Gain Configuration and chose to use 2 ADA4522 (since it has an input range of 0-55V and low a low offset voltage, see attached schematic). In the simulation the buffer circuit worked without a problem, but in reality I get huge offset voltages between the non-inverting and the inverting input of the ADA4522 (e.g. I get 18.834V on the +IN and 19.745V on -IN in the setup in the attached schmatic).
I already asked about this issue in the analog devices forum (Analog Devices Forum) using a slightly different setup. Apparently there is a problem with connecting the ADA4522 to a high source impedance. Since this can not be avoided in my circuit I am looking for a different way to buffer the voltage. I was thinking of using a different Opamp, even though there are less parts available with the required input range. Furthermore I need low voltage offset < 1mV. But before I just pick a new part I wanted to ask if anybody here knows an Opamp that would work in this case and does not have an issue with high input resistance.
I would appreciate your suggestions/comments.
Regards Dave
In my design I need to buffer about 45V-48V and about 30V. For this purpose I want to use two Opamps in Unity Gain Configuration and chose to use 2 ADA4522 (since it has an input range of 0-55V and low a low offset voltage, see attached schematic). In the simulation the buffer circuit worked without a problem, but in reality I get huge offset voltages between the non-inverting and the inverting input of the ADA4522 (e.g. I get 18.834V on the +IN and 19.745V on -IN in the setup in the attached schmatic).
I already asked about this issue in the analog devices forum (Analog Devices Forum) using a slightly different setup. Apparently there is a problem with connecting the ADA4522 to a high source impedance. Since this can not be avoided in my circuit I am looking for a different way to buffer the voltage. I was thinking of using a different Opamp, even though there are less parts available with the required input range. Furthermore I need low voltage offset < 1mV. But before I just pick a new part I wanted to ask if anybody here knows an Opamp that would work in this case and does not have an issue with high input resistance.
I would appreciate your suggestions/comments.
Regards Dave