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Silicon Labs’ Si834x Family of Smart Switches

September 18, 2019 by Luke James

Silicon Labs recently introduced its Si834x family of compact and robust smart switches. Designed for use in harsh industrial environments, they drive resistive and inductive loads.

The Si834x family of isolated switches from Silicon Labs is designed to drive resistive and inductive loads in harsh industrial environments. 

Galvanically isolated using proprietary complementary metal-oxide semiconductor-based technology, this family of switches is far more reliable than those with optocoupler-based isolation; it enables common-mode transient immunity of more than 100kV/µs.

The isolation technique used is the same as that used in an optocoupler, save for the fact that an RF carrier is modulated across the isolation barrier instead. This creates a reliable isolation path that does not warrant initialisation during start up.


The Si834x Family

With 4 isolated high or low-side switches and low on-resistance (145 mΩ RON), the Si834x smart switches are ideal for driving the aforementioned loads (e.g. solenoids, relays, and lamps) that are commonly found in industrial control systems, such as programmable logic controllers.


Si834x smart watch.

The Si834x smart switch. Image courtesy of Silicon Labs.


The switches also provide 700mA of continuous current (which makes them compliant with the IEC 61131-2 standard) alongside comprehensive protection, diagnostic reporting, advanced configuration, and monitoring and control for industrial automation systems.

As vice president and general manager of Silicon Labs' power products, Brian Mirkin, said in a company press release:

"The Si834x family expands [its] broad isolator portfolio, complementing [its] programmable-logic controller input isolators and isolated field-effect transistor drivers to provide a complete solution.

“The Si834x switches outperform opto-isolators, power field-effect transistors and other competing options by offering a fully-integrated 24 V digital output solution with best-in-class switch protection, flexible configuration, and comprehensive diagnostic feedback."

The 6 products of the Si834x family offer 4 output channels, up to 0.7 A continuous output current, and a supply range of −32 V to 9 V.


Table of Silicon Labs' smart switches.

A table that details the entire family of Silicon Labs’ switches. Each entry in the series operates over a temperature range of −40°C to 120°C.


Potential Applications

Due to the sophisticated switch and load-monitoring techniques used—combined with flexibility and fast responses to changing conditions—the switches are extremely robust and can be used in a variety of applications. As they both drive a wide range of loads and even safely survive unexpected loads with rapid recovery.

Example applications include smart solid-state relays, motion controllers, industrial data acquisition devices, and programmable logic controllers. Due to the robust nature of these switches—particularly the temperature range, rapid recovery, and monitoring and control characteristics—they are suited for deployment in harsh industrial settings.

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