The analog input stage of the AMC1303 is a fully differential amplifier feeding the switched-capacitor input of a second-order, delta-sigma (ΔΣ) modulator stage that digitizes the input signal into a 1-bit output stream. The isolated data output DOUT of the converter provides a stream of digital ones and zeros that is synchronous to the internally-generated clock at the CLKOUT pin (active on AMC1303Mx derivates only) with a frequency as specified in the Switching Characteristics table. The time average of this serial bit-stream output is proportional to the analog input voltage.
The Functional Block Diagram section shows a detailed block diagram of the AMC1303. The analog input range is tailored to directly accommodate a voltage drop across a shunt resistor used for current sensing. The SiO2-based capacitive isolation barrier supports a high level of magnetic field immunity as described in the application report ISO72x Digital Isolator Magnetic-Field Immunity (SLLA181A), available for download at www.ti.com. The extended clock frequency of 20 MHz on the AMC1303xxx20 supports faster control loops and higher performance levels compared to the other solutions available on the market.