New isolated smart switches aims better reliability and performance than optocoupler-based isolation


ByAyush Kumar 0

Si834x isolated switches to drive loads in harsh industrial environments

Silicon Labs  has introduced a new range of compact isolated smart switches. These switches are designed to drive heavy loads, even in the harsh industrial environments. The new Si834x isolated switches are capable of driving resistive and inductive loads such as solenoids, relays and lamps used in industrial control systems. This also includes 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, aimed at offering better reliability and performance than legacy optocoupler-based isolation.


The Si834x isolated switch family supports high-side and low-side switch options, low on-resistance (145 mΩ RON) and up to 700 mA of continuous current. These features make it compliant with the IEC 61131-2 standard too. The switch logic interface is as simple as four low-power CMOS digital inputs and flexible as a full serial peripheral interface (SPI). This makes it capable for controlling up to 128 channels with four MCU pins.


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. A multi-voltage smart clamp efficiently handles unlimited amount of demagnetization energy. Over-current protection includes an inrush current mode allowing the switch to drive challenging loads. These switches can achieve better inductive load-driving performance than competing devices and safer overload by employing an innovative, rapid manipulation of switch impedance and clamp voltage.


These isolated switches feature a logic interface with eight separate diagnostic reports. Further, 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 fault monitoring system helps gain information about how the switches and their loads are behaving on the other side of the isolation barrier.


Pricing and Availability

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 center pad (ePAD). The Si834x4x switches with a parallel interface are priced at $1.90 each (USD) in 100,000-unit quantities. The Si834x8x switches supporting SPI are priced at $2.09 each in 100,000-unit quantities. Silicon Labs also offers Si834x evaluation kits with either a parallel or SPI interface and sinking/sourcing output options. For more information and to request device samples, visit


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