9.1 Overview

The ISO7041 device uses edge encoding of data with an ON-OFF keying (OOK) modulation scheme to transmit the digital data across a silicon dioxide isolation barrier. The transmitter uses a high frequency carrier signal to pass data across the barrier representing a signal edge transition. Using this method achieves very low power consumption and high immunity. The receiver demodulates the carrier signal after advanced signal conditioning and produces the output through a buffer stage. For low data rates, a refresh logic option is available to make sure the output state matches the input state. The ENx pins of side A and side B must be tied low to enable refresh or high to disable refresh. Advanced circuit techniques are used to maximize the CMTI performance and minimize the radiated emissions due to the high frequency carrier and IO buffer switching. The conceptual block diagram of a digital capacitive isolator, Figure 14, shows a functional block diagram of a typical channel.