Texas Instruments' INA149 is a precision unity-gain difference amplifier with a high input common-mode voltage range. It is a single, monolithic device that consists of a precision op amp and an integrated thin-film resistor network. The INA149 can accurately measure small differential voltages in the presence of common-mode signals up to ±275 V. The INA149 inputs are protected from momentary common-mode or differential overloads of up to 500 V.
In many applications, where galvanic isolation in not required, the INA149 can replace isolation amplifiers. This ability can eliminate costly isolated input-side power supplies and the associated ripple, noise, and quiescent current. The excellent 0.0005% nonlinearity and 500 kHz bandwidth of the INA149 are superior to those of conventional isolation amplifiers.