7 Detailed Description

7.1 Overview

The AMC0x00R is a precision, galvanically isolated amplifier with a ±250mV, differential input and single-ended,

ratiometric output. The input stage of the device drives a second-order, delta-sigma (ΔΣ) modulator. The

modulator converts the analog input signal into a digital bitstream that is transferred across the isolation barrier

that separates the high-side from the low-side.

On the low-side, the received bitstream is processed by an analog filter that outputs a GND2-referenced,

single-ended signal at the OUT pin. This single-ended output signal is proportional to the input signal. The

full-scale output voltage of the isolated amplifier is equal to the voltage applied to the REFIN pin.

The SiO2-based, capacitive isolation barrier supports a high level of magnetic field immunity, as described in the

ISO72x Digital Isolator Magnetic-Field Immunity application note. The digital modulation used in the AMC0x00R

transmits data across the isolation barrier. This modulation, and the isolation barrier characteristics, result in high

reliability and high common-mode transient immunity.

7.2 Functional Block Diagram

ΔΣ Modulator

GND1

INP

INN

VDD1

Reference

20 MHz Oscillator

VDD2

OUT

REFIN

GND2

Analog Filter

1.44V

+

–

216kΩ

96kΩ

DAC

7.3 Feature Description

7.3.1 Analog Input

As shown in Figure 7-1, input of the AMC0x00R has a fully differential, switched-capacitor circuit with a dynamic

input impedance of 27.5kΩ.

The sampling capacitor is continuously charged and discharged with a frequency of 20MHz. With the S1

switches closed, CIND charges to the voltage difference across VINP and VINN. For the discharge phase, both S1

switches open first and then both S2 switches close. CIND discharges to approximately AGND + 0.8V during this

phase.

AMC0300R, AMC0200R

SBASAR9A – DECEMBER 2025 – REVISED JUNE 2026

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