The **LSMT2-42140-R** is an ultra-miniature, surface-mount (SMD) tactile switch commonly used in consumer electronics where space is extremely limited. This part is part of the "micro-tact" family of switches. --- ### 1. Technical Specifications The following table outlines the primary electrical and mechanical characteristics of the component: | Feature | Specification | | :--- | :--- | | **Type** | Tactile Switch (Push Button) | | **Mounting Style** | Surface Mount Device (SMD/SMT) | | **Dimensions** | 4.2mm x 3.2mm (Approximate base size) | | **Height** | 2.5mm (Typical for this series) | | **Operating Force** | 160gf to 240gf (Depending on specific sub-variant) | | **Contact Current Rating** | 50mA @ 12V DC | | **Contact Resistance** | < 100 mΩ | | **Travel (Stroke)** | 0.25mm ± 0.1mm | | **Operating Life** | ~50,000 to 100,000 cycles | --- ### 2. Physical Construction The part is designed for automated assembly processes. Key components include: * **Actuator (Stem):** Usually made of high-temperature plastic (LCP) to withstand reflow soldering. * **Contact Dome:** A stainless steel or phosphor bronze dome that provides the "click" tactile feedback and completes the circuit. * **Terminals:** Silver-plated leads for high conductivity and easy soldering. * **Base:** Heat-resistant molded resin. --- ### 3. Application Use-Cases Due to its small footprint, the LSMT2-42140-R is typically found in: 1. **Wearables:** Smartwatches and fitness trackers. 2. **Portable Medical Devices:** Blood glucose monitors or handheld diagnostic tools. 3. **Consumer Gadgets:** Bluetooth headsets, remote controls, and digital cameras. 4. **Internet of Things (IoT):** Reset buttons or user input buttons on compact PCB modules. --- ### 4. Circuit Diagram (Internal) The switch is a **Single Pole Single Throw (SPST)**, Normally Open (NO) device. ```text (Pin 1) ----\ (Switch) /---- (Pin 2) \____/ (When pressed, circuit closes) ``` ---