The operation of an Si875x 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 Si875x channel is shown in the figure below.

MODULATOR

DEMODULATOR

RF OSCILLATOR

Semiconductor-

Based Isolation

Barrier

Transmitter

Receiver

A

B

Figure 2.3. 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. See figure below for more details.

Input Signal

Output Signal

Modulation Signal

Figure 2.4. Modulation Scheme

2.1 Device Behavior

The following are truth tables for the Si875x family.

Table 2.1. Si8751 Truth Table

VDD

IN

Gate

Powered

H

H

Powered

L

L

Unpowered

X

L

Table 2.2. Si8752 Truth Table

Input Current

Gate

> If(TH)

H

< If(TH)

L

Si8751/52 Data Sheet • System Overview

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

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206331A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • July 27, 2022

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