SI861X Datasheet, PDF (3/38 Pages) Silicon Laboratories – Low-Power Single and Dual-Channel Digital Isolators

2. System Overview
Si861x/2x Data Sheet
System Overview
2.1 Theory of Operation
The operation of an Si861x/2x 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 Si861x/2x channel is shown in the figure below.
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 trans-
mitter, input A modulates the carrier provided by an RF oscillator using on/off keying. The Receiver contains a demodulator that de-
codes 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 improved immunity
to magnetic fields. See the following figure for more details.
Figure 2.2. Modulation Scheme
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