The **LCA210LS** is a dual-pole, normally open (1-Form-A) Solid State Relay (SSR) manufactured by IXYS Integrated Circuits Division (formerly Clare). It is designed to provide high-speed, noise-free switching in a compact package. --- ## 1. Core Specifications The following table highlights the critical electrical characteristics of the LCA210LS: | Parameter | Specification | | :--- | :--- | | **Relay Type** | Solid State (OptoMOS) | | **Contact Form** | Dual 1-Form-A (2x Normally Open) | | **Load Voltage** | 350V (Peak) | | **Load Current** | 170mA (RMS/DC) | | **On-Resistance (Max)** | 35 $\Omega$ | | **Input Control Current** | 2mA to 50mA | | **Isolation Voltage** | 3750Vrms | | **Package Type** | 8-Pin S Gull Wing (Surface Mount) | --- ## 2. Internal Components & Working Principle The LCA210LS operates using **OptoMOS** technology, which integrates an input infrared LED with output photovoltaic cells and MOSFETs. ### A. Input Side (Control) * **Infrared LED:** When a small DC current (typically 2-5mA) flows through the input pins, the LED emits light. * **Isolation:** There is no electrical connection between the input and output; they are coupled optically, providing high galvanic isolation (3750Vrms). ### B. Output Side (Switching) * **Photovoltaic Array:** Receives the light from the LED and converts it into a voltage. * **MOSFET Switches:** This voltage triggers the gates of two MOSFETs. Because it uses MOSFETs, it can switch both AC and DC loads without the "zero-crossing" limitations of Triacs. --- ## 3. Key Electronic Features * **Low Drive Power:** It requires very little current to trigger, making it directly compatible with CMOS and TTL logic circuits (microcontrollers). * **No Moving Parts:** Unlike electromechanical relays, it does not suffer from contact bounce, arcing, or mechanical wear, leading to a much longer lifespan. * **High Input-to-Output Isolation:** Protects sensitive low-voltage control circuitry from high-voltage transients on the load side. * **Linear Operation:** It provides low distortion for small signal switching, making it suitable for telecommunications. --- ## 4. Common Applications 1. **Telecommunications:** Tip/Ring switching, hook switch emulation, and dial pulsing. 2. **Instrumentation:** Multiplexers, data acquisition, and automatic test equipment (ATE). 3. **Industrial Controls:** Replacing small reed relays or power-hungry mechanical relays. 4. **Security:** Sensor activation and alarm signaling. ---