The **FSM5JS** is a part number typically associated with **Tactile Switches** (Tact Switches) manufactured by companies like TE Connectivity (ALCOSWITCH) or similar electronic component vendors. These are miniature, momentary push-button switches commonly used in low-power signal switching. --- ### 1. Key Technical Specifications Below are the primary electronic and physical characteristics of the FSM5JS series: | Property | Specification (Typical) | | :--- | :--- | | **Switch Type** | Tactile (Momentary) | | **Mounting Type** | Through-Hole (THT) | | **Actuation Force** | 160gf (Grams-force) | | **Contact Rating** | 50mA @ 12VDC | | **Contact Resistance** | 100 mΩ Max | | **Life Cycle** | ~100,000 Cycles | | **Actuator Style** | Standard Round Button | --- ### 2. Internal Electronic Structure The FSM5JS operates as a **SPST-NO (Single Pole Single Throw - Normally Open)** switch. * **Non-Actuated State:** The internal metal dome is raised, and there is no electrical continuity between the input and output pins. * **Actuated State:** When the button is pressed, the dome collapses (providing tactile feedback) and bridges the internal contacts. * **Release:** The dome springs back to its original shape, breaking the circuit. --- ### 3. Pinout and Layout Most components in the FSM series follow a standard **6x6 mm** footprint with four pins. * **Parallel Wiring:** Although there are four pins, they are usually internally connected in pairs (Pins 1 & 2 are tied together; Pins 3 & 4 are tied together). * **Purpose:** This design provides mechanical stability on the PCB and allows the switch to act as a "jumper" or bridge in simple circuit traces. --- ### 4. Applications Because of its small size and reliable "click" feel, the FSM5JS is found in: 1. **Consumer Electronics:** Reset buttons, volume controls, or mode selectors. 2. **Industrial:** Control panels and interface boards. 3. **Prototyping:** Breadboard-friendly testing (when leads are bent slightly) and DIY microcontroller projects (Arduino/ESP32). --- ### 5. Part Number Breakdown (Example) * **FSM:** Tactile Switch Series. * **5:** Usually refers to the height of the actuator (e.g., 5.0mm). * **J:** Often denotes the specific packaging or material (e.g., High-temperature materials). * **S:** Often refers to specific terminal plating or force variations.