Four channel isolated smart switch for harsh industrial environments
Silicon Labs has launched an isolated smart switch family designed to drive any load, even in the harshest industrial environments.
The Si834x isolated switch is intended to drive 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.
Each smart 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. A 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 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.
“The new Si834x isolated smart switch family embodies three generations of Silicon Labs’ isolation innovation for industrial automation,” said Brian Mirkin, Vice President and General Manager of Silicon Labs’ power products. “The Si834x family expands our broad isolator portfolio, complementing our PLC input isolators and isolated FET drivers to provide a complete solution. The Si834x switches outperform opto-isolators, power FETs 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 Si834x uses a rapid manipulation of switch impedance and clamp voltage for improved inductive load-driving performance and avoid the need for complicated cooling. 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, improving system availability.
The isolated switches use a logic interface with eight separate diagnostic reports, allowing control of each switch with diagnostic communication independent of the switch control signals across the isolation barrier. The diagnostics are configured, monitored and cleared through SPI or exposed on active-low, open-drain indicator pins for easy access.
Samples and production quantities of the 4-channel Si834x isolated smart switches are available now in a compact 9 mm x 9 mm DFN-32 package with an exposed centre pad (ePAD). The Si834x4x smart switch with a parallel interface is priced at $1.90 each (USD) in 100,000-unit quantities. The Si834x8x switch supporting SPI is priced at $2.09 each in 100,000-unit quantities. To simplify development and accelerate time to market, Silicon Labs offers Si834x evaluation kits with either a parallel or SPI interface and sinking/sourcing output options.
silabs.com/isolated-smart-switch
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