The differential amplifier input stage of the AMC1400 feeds a second-order, switched-capacitor, feed-forward ΔΣ modulator. The gain of the differential amplifier is set by internal precision resistors with a differential input impedance of R_IND. The modulator converts the analog input signal into a bitstream that is transferred across the isolation barrier, as described in the Section 7.3.2 section.

There are two restrictions on the analog input signals INP and INN. First, if the input voltages V_INP or V_INN exceed the range specified in the Section 6.1 table, the input currents must be limited to the absolute maximum value, because the electrostatic discharge (ESD) protection turns on. In addition, the linearity and parametric performance of the device are ensured only when the analog input voltage remains within the linear full-scale range (V_FSR) and within the common-mode input voltage range (V_CM), as specified in the Section 6.3 table.