SI8442AB-C-IS Silicon Laboratories Inc, SI8442AB-C-IS Datasheet - Page 21

• Manufacturer Part Number: SI8442AB-C-IS
• Manufacturer: Silicon Laboratories Inc

Specifications of SI8442AB-C-IS

• Operating Supply Voltage (typ): 3.3/5V
• Lead Free Status / RoHS Status: Compliant

3. Application Information
3.1. Theory of Operation
The operation of an Si844x channel is analogous to that of an opto coupler, except an RF carrier is modulated
instead of light. This simple architecture provides a robust isolated data path and requires no special
considerations or initialization at start-up. A simplified block diagram for a single Si844x channel is shown in
Figure 11.
A channel consists of an RF Transmitter and RF Receiver separated by a semiconductor-based isolation barrier.
Referring to the Transmitter, input A modulates the carrier provided by an RF oscillator using on/off keying. The
Receiver contains a demodulator that decodes the input state according to its RF energy content and applies the
result to output B via the output driver. This RF on/off keying scheme is superior to pulse code schemes as it
provides best-in-class noise immunity, low power consumption, and better immunity to magnetic fields. See
Figure 12 for more details.
A
Transmitter
OSCILLATOR
MODULATOR
Figure 11. Simplified Channel Diagram
RF
Figure 12. Modulation Scheme
Semiconductor-
Based Isolation
Rev. 1.2
Barrier
DEMODULATOR
Modulation Signal
Si8440/41/42/45
Output Signal
Input Signal
Receiver
B
21