The high-impedance input stage of the AMC1333M10 feeds a second-order, switched-capacitor, feed-forward ΔΣ modulator. The modulator converts the analog signal into a bitstream that is transferred over the isolation barrier, as described in the Section 7.3.3 section. The high-impedance and low bias-current input makes the AMC1333M10 suitable for isolated, high-voltage-sensing applications that typically employ high-impedance resistor dividers.

For reduced offset and offset drift, the input buffer is chopper-stabilized with the chopping frequency set at f_CLK / 32. Figure 7-1 shows the spur at 312.5 kHz that is generated by the chopping frequency for a modulator clock of 10 MHz.

There are two restrictions on the analog input signals (INP and INN). First, if the input voltage exceeds the input range specified in the Section 6.1 table, the input current must be limited to 10 mA because the device input electrostatic discharge (ESD) diodes turn on. Second, the linearity and noise performance of the device are ensured only when the differential analog input voltage remains within the specified linear full-scale range V_FSR and within the specified input common-mode voltage range V_CM, as shown in Figure 7-2 and as specified in the Section 6.3 table.