6 Detailed Description

6.1 Overview

The AMC0136 is a single-channel, second-order, CMOS, delta-sigma (ΔΣ) modulator with a high impedance

input, designed for high resolution voltage measurements. The isolated output of the converter (DOUT) provides

a stream of digital ones and zeros synchronous to the external clock applied to the CLKIN pin. The time average

of this serial output is proportional to the analog input voltage.

The modulator shifts the quantization noise to high frequencies; therefore, use a digital low-pass digital filter,

such as a Sinc filter at the device output to increase overall performance. This filter also converts the 1-bit data

stream at a high sampling rate into a higher-bit data word at a lower rate (decimation). Use a microcontroller

(μC) or field-programmable gate array (FPGA) to implement the filter.

The overall performance (speed and resolution) depends on the selection of an appropriate oversampling ratio

(OSR) and filter type. A higher OSR results in higher resolution while operating at a lower refresh rate. A lower

OSR results in lower resolution, but provides data at a higher refresh rate. This system allows flexibility with the

digital filter design and is capable of analog-to-digital conversion results with a dynamic range exceeding 89dB

with OSR = 256.

The silicon-dioxide (SiO2) based capacitive isolation barrier supports a high level of magnetic field immunity;

see the ISO72x Digital Isolator Magnetic-Field Immunity application note. The AMC0136 uses an on-off keying

(OOK) modulation scheme to transmit data across the isolation barrier. This modulation and the isolation barrier

characteristics, result in high reliability in noisy environments and high common-mode transient immunity.

6.2 Functional Block Diagram

DVDD

DOUT

DGND

AGND

INP

SNSN

AVDD

CLKIN

Modulator

Diagnostics

Digital

Interface

www.ti.com

AMC0136

SBASAZ0A – AUGUST 2024 – REVISED DECEMBER 2024

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Product Folder Links: AMC0136