The AD628 is a precision difference amplifier that combines excellent dc performance with high common-mode rejection over a wide range of frequencies. When used to scale high voltages, it allows simple conversion of standard control voltages or currents for use with single-supply ADCs. A wideband feedback loop minimizes distortion effects due to capacitor charging of Σ-Δ ADCs.
A reference pin (VREF) provides a dc offset for converting bipolar to single-sided signals. The AD628 converts +5 V, +10 V, ±5 V, ±10 V, and 4 to 20 mA input signals to a single-ended output within the input range of single-supply ADCs.
The AD628 has an input common mode and differential mode operating range of ±120 V. The high common mode, input impedance makes the device well suited for high voltage measurements across a shunt resistor. The inverting input of the buffer amplifier is available for making a remote Kelvin connection.