6 Detailed Description

6.1 Overview

The AMC3301 is a fully differential, precision, isolated amplifier with a fully integrated DC/DC converter that

can supply the device from a single 3.3-V or 5-V voltage supply on the low-side. The input stage of the device

consists of a fully differential amplifier that drives a second-order, delta-sigma (ΔΣ) modulator. The modulator

uses an internal voltage reference and clock generator to convert the analog input signal to a digital bitstream.

The drivers (termed TX in the Functional Block Diagram) transfer the output of the modulator across the isolation

barrier that separates the high-side and low-side voltage domains. As shown in the Functional Block Diagram,

the received bitstream and clock are synchronized and processed by a fourth-order analog filter on the low-side

and presented as a differential output of the device

The signal path is isolated by a double capacitive silicon dioxide (SiO2) insuation barrier, whereas power

isolation uses an on-chip transformer separated by a thin-film polymer as the insulating material.

6.2 Functional Block Diagram

AMC3301

û Modulator

HGND

INP

INN

OUTP

OUTN

GND

DCDC_IN

DCDC_GND

LDO_OUT

VDD

DIAG

DCDC_OUT

DCDC_HGND

HLDO_IN

HLDO_OUT

NC

Resonator

And

Driver

LDO

Rectifier

LDO

Diagnostics

Analog Filter

6.3 Feature Description

6.3.1 Analog Input

The differential amplifier input stage of the AMC3301 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 signal into a bitstream that is transferred across the

isolation barrier, as described in the Data 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 current must be limited to the

absolute maximum value, because the device input electrostatic discharge (ESD) diodes turns on. In addition,

the linearity and parametric performance of the device are ensured only when the analog input voltage remains

within linear full-scale range (VFSR) and within the common-mode input voltage range (VCM) as specified in the

Recommended Operating Conditions table.

AMC3301

SBAS917C – AUGUST 2019 – REVISED MAY 2025

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