SI8435 SILABS [Silicon Laboratories], SI8435 Datasheet - Page 19

• Manufacturer Part Number: SI8435
• Description: TRIPLE-CHANNEL DIGITAL ISOLATOR
• Manufacturer: SILABS [Silicon Laboratories]

Si8430/31/35
3. Application Information
3.1. Theory of Operation
The operation of an Si8430 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 Si8430 channel is shown in
Figure 11. A channel consists of an RF transmitter and receiver separated by a transformer.
Referring to the transmitter, input A modulates the carrier provided by an RF oscillator using on/off keying and
applies the resulting waveform to the primary of the transformer. 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.
TRANSMITTER
RF
RECEIVER
OSCILLATOR
A
B
MODULATOR
DEMODULATOR
Figure 11. Simplified Channel Diagram
3.2. Eye Diagram
Figure 12 illustrates an eye-diagram taken on an Si8430. The test used an Anritsu (MP1763C) Pulse Pattern
Generator for the data source. The output of the generator's clock and data from an Si8430 were captured on an
oscilloscope. The results illustrate that data integrity was maintained even at the high data rate of 150 Mbps. The
results also show that very low pulse width distortion and very little jitter were exhibited.
Figure 12. Eye Diagram
Rev. 0.3
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