Based on technical specifications, the **KMMLS-333-R** is an illuminated, right-angle, surface-mount (SMT) tactile switch. These components are commonly used in consumer electronics, industrial controls, and medical devices where space is limited and user feedback (visual and tactile) is required. --- ### 1. General Specifications The KMMLS-333-R belongs to the category of **Illuminated Tactile Switches**. Below are the core mechanical and electrical characteristics: | Feature | Specification | |:---|:---| | **Mounting Type** | Surface Mount (SMT) / Right Angle | | **Circuitry** | SPST (Single Pole Single Throw) | | **Switch Function** | Off-Mom (Momentary) | | **Actuation Force** | Typically 160gf to 250gf (grams-force) | | **Travel Distance** | ~0.25mm | | **Operating Life** | 100,000 to 500,000 cycles | | **LED Color** | Red (indicated by the "-R" suffix) | --- ### 2. Electronic Component Breakdown #### A. The Switch Mechanism (Tactile) The switch functions as a physical interface. When the plunger is pressed, it bridges a metal dome to the PCB pads, completing the circuit. * **Contact Rating:** Usually rated for low current (e.g., 50mA at 12V DC). * **Contact Resistance:** Max 100mΩ. * **Insulation Resistance:** Min 100MΩ at 100V DC. #### B. The Integrated LED The "R" in the part number indicates a **Red LED**. Because the LED and the switch are integrated into a single housing, they share the same physical footprint but operate on independent circuits. * **Forward Voltage ($V_f$):** Typically 1.8V to 2.2V for Red. * **Forward Current ($I_f$):** Typically 20mA. * **Polarity:** The PCB layout must account for the specific Anode (+) and Cathode (-) pins for the LED to function. #### C. Physical Orientation (Right Angle) Unlike standard tactile switches that are pressed "down" toward the PCB, the **Right Angle** design allows the button to be pressed from the side (parallel to the board). This is ideal for: * Side-mounted power buttons. * Edge-located reset switches. * User interfaces on the thin side of a device casing. --- ### 3. Typical Pin Configuration While you should always consult the specific datasheet for the manufacturer (likely *Kailh* or a similar brand using this numbering), the pinout generally follows this logic: ```text Pin 1 & 2: Switch Contacts (Normally Open) Pin 3: LED Anode (+) Pin 4: LED Cathode (-) ``` --- ### 4. Application Considerations * **Current Limiting Resistor:** You must use a resistor in series with the LED pins to prevent the Red LED from burning out. * **Soldering:** Being an SMT component, it is designed for reflow soldering. Excessive heat during manual soldering can melt the internal plastic plunger or damage the LED. * **Debouncing:** Like all mechanical switches, this part will exhibit "contact bounce." Software or hardware debouncing (usually 5-10ms) is required for clean signal processing.