7 Detailed Description

7.1 Overview

The AMC1301 is a fully differential, precision, isolated amplifier. The input stage of the device consists of a

fully differential amplifier that 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 a fourth-order analog filter

that outputs a differential signal at the OUTP and OUTN pins that is proportional to the input signal.

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 AMC1301

to transmit data across the isolation barrier, and the isolation barrier characteristics, result in high reliability and

common-mode transient immunity.

7.2 Functional Block Diagram

AMC1301

ΔΣ Modulator

GND1

INP

INN

VDD1

Diagnostics

VDD2

OUTP

OUTN

GND2

Analog Filter

7.3 Feature Description

7.3.1 Analog Input

The differential amplifier input stage of the AMC1301 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 RIND. The modulator converts the analog input signal into a bitstream that is transferred across the

isolation barrier, as described in the Isolation Channel Signal Transmission section.

There are two restrictions on the analog input signals (INP and INN). First, if the input voltages VINP or VINN

exceed the range specified in the Absolute Maximum Ratings 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 (VFSR) and within the common-mode input voltage range (VCM), as specified in the

Recommended Operating Conditions table.

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AMC1301

SBAS667G – APRIL 2016 – REVISED APRIL 2023

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