The differential analog input (AINP and AINN) of the AMC1305 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 synchronous to the externally-provided clock source at the CLKIN pin with a frequency in the range of 5 MHz to 20.1 MHz. 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 AMC1305. 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 external clock input simplifies the synchronization of multiple current-sense channels on the system level. The extended frequency range of up to 20.1 MHz supports higher performance levels compared to other solutions available on the market.