SI8285 Datasheet, PDF (3/32 Pages) Silicon Laboratories – System Safety Features

2. System Overview
Si8285/86 Data Sheet
System Overview
2.1 Isolation Channel Description
The operation of a Si8285 or Si8286 channel is analogous to that of an optocoupler and gate driver, 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 Si828x channel is shown in the figure below.
Transmitter
RF
OSCILLATOR
Receiver
VDD
A
Input
Logic
MODULATOR
Semiconductor-
Based Isolation
Barrier
DEMODULATOR
+
NOISE FILTER
VH
VL
Gnd
Figure 2.1. Simplified Channel Diagram
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.
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