Silicon Labs: isolated smart switches drive any load in harsh industrial environments

Silicon Labs has introduced a family of compact, robust isolated smart switches designed to drive any load, even in the harshest industrial environments. The new Si834x isolated switches are ideal for driving resistive and inductive loads such as solenoids, relays and lamps used in industrial control systems including programmable logic controllers (PLCs), I/O modules, relay drivers and servo motor controllers. Each switch is galvanically isolated for safety using Silicon Labs’ CMOS-based isolation technology, offering better reliability and performance than legacy optocoupler-based isolation, including high common-mode transient immunity (CMTI) of more than 100 kV/µs.

The Si834x isolated switch family supports high-side and low-side switch options, low on-resistance (145 mΩ RON), up to 700 mA of continuous current compliant with the IEC 61131-2 standard, comprehensive protection and diagnostic reporting, and advanced configuration, monitoring and control for industrial automation systems. The switch logic interface can be as simple as four low-power CMOS digital inputs or as rich and flexible as a full serial peripheral interface (SPI) capable of controlling up to 128 channels with four MCU pins.

Sophisticated switch and load monitoring techniques combined with fast responses to changing conditions make the Si834x switches extremely robust, flexible solutions for driving a wide range of loads. Each switch can detect an open-circuit condition and is protected against over-current, over-voltage from demagnetization (inductive kick or flyback voltage) and over-temperature conditions. An innovative multi-voltage smart clamp efficiently handles an unlimited amount of demagnetization energy. Over-current protection includes an inrush current mode not found in competing products, allowing the switch to drive challenging loads.

The Si834x switches achieve better inductive load-driving performance than competing devices and safer overload protection without the same inefficiency, loss of lifetime reliability, or the need for complicated cooling solutions by employing an innovative, rapid manipulation of switch impedance and clamp voltage. While other solutions entering into a fault state may shut down, the Si834x switches can continue operation in a constrained but functional state with reduced channel performance, dramatically improving system uptime.

The isolated switches feature a sophisticated logic interface with eight separate diagnostic reports, offering an unprecedented level of detail and control for each switch and making the Si834x devices the most flexible switches on the market. Diagnostics are configured, monitored and cleared through SPI or exposed on active-low, open-drain indicator pins for easy access. Diagnostic communication is independent of the switch control signals across the isolation barrier. Separate isolation channels and constant fault monitoring ensure the highest level of device reliability, providing system operators with detailed information about how the switches and their loads are behaving on the other side of the isolation barrier.

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