SI8410BB-D-IS Datasheet, PDF (17/30 Pages) Silicon Laboratories – LOW-POWER SINGLE AND DUAL-CHANNEL DIGITAL ISOLATORS

Si8410/20/21
2. Functional Description
2.1. Theory of Operation
The operation of an Si84xx 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 Si84xx channel is shown in
Figure 3.
Transmitter
Receiver
RF
OSCILLATOR
d _{Semiconductor-}
e _A
MODULATOR
Based Isolation
DEMODULATOR
B
Barrier
mendigns Figure 3. Simplified Channel Diagram
m ^{s 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
o ^{e 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
c ^{D provides best-in-class noise immunity, low power consumption, and better immunity to magnetic fields. See}
Figure 4 for more details.
Re _{ew Input Signal}
Not _for ^{N Modulation Signal}
Output Signal
Figure 4. Modulation Scheme
Rev. 1.5
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