TX IN

RX OUT

Carrier signal through

isolation barrier

TX IN

Oscillator

OOK

Modulation

Transmitter

Emissions

Reduction

Techniques

TX Signal

Conditioning

Envelope

Detection

RX Signal

Conditioning

Receiver

EN

RX OUT

Capacitive

Isolation

Barrier

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16

ISO7841, ISO7841F

SLLSEM3F – NOVEMBER 2014 – REVISED APRIL 2016

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8 Detailed Description

8.1 Overview

The ISO7841 device uses an ON-OFF Keying (OOK) modulation scheme to transmit the digital data across a

silicon-dioxide based isolation barrier. The transmitter sends a high-frequency carrier across the barrier to

represent one digital state and sends no signal to represent the other digital state. The receiver demodulates the

signal after advanced signal conditioning and produces the output through a buffer stage. If the EN pin is low

then the output goes to high impedance. The ISO7841 device also incorporates advanced circuit techniques to

maximize the CMTI performance and minimize the radiated emissions because of the high-frequency carrier and

IO buffer switching. The conceptual block diagram of a digital capacitive isolator, Figure 11, shows a functional

block diagram of a typical channel.

8.2 Functional Block Diagram

Figure 11. Conceptual Block Diagram of a Digital Capacitive Isolator

Figure 12 shows a conceptual detail of how the ON-OFF keying scheme works.

Figure 12. On-Off Keying (OOK) Based Modulation Scheme