The **JS0204FP4-R** is a specific surface-mount (SMD) low-profile DIP switch manufactured by **C&K Components** (now part of Littelfuse). These switches are commonly used to set configurations, addresses, or modes on printed circuit boards (PCBs). ### 1. Technical Specifications The following table summarizes the primary electrical and mechanical characteristics of the JS0204FP4-R: | Feature | Specification | | :--- | :--- | | **Switch Type** | DIP (Dual In-line Package) | | **Number of Positions** | 4 Positions | | **Actuator Type** | Flush / Recessed | | **Actuator Style** | Slide | | **Mounting Type** | Surface Mount (SMD/SMT) | | **Pitch** | 1.27 mm (Half Pitch) | | **Current Rating** | 25mA @ 24V DC (Switching) / 100mA @ 50V DC (Non-switching) | | **Operating Temperature** | -40°C to +85°C | | **Mechanical Life** | 1,000 cycles | --- ### 2. Physical Construction & Design The JS series is designed for space-constrained applications. * **Half-Pitch Design:** Unlike standard 2.54mm pitch DIP switches, this part uses a **1.27mm pitch**. This reduces the overall footprint by 50%, making it ideal for handheld devices or compact industrial sensors. * **Flush Actuator:** The "FP" in the part number indicates a **Flush Actuator**. This means the sliders are recessed, preventing accidental changes to the settings. A small tool or stylus is usually required to toggle the switch. * **Materials:** * **Housing:** High-temperature thermoplastic (PPS), UL94V-0 rated. * **Contacts:** Gold-plated over nickel to ensure low contact resistance and prevent oxidation. --- ### 3. Application Use Cases This component is typically found in the following electronic environments: 1. **Industrial Automation:** Setting unique Modbus or CAN bus slave IDs on sensor nodes. 2. **Consumer Electronics:** Hard-coding regional settings or hardware revision flags. 3. **Telecommunications:** Configuring basic parameters on network interface cards. 4. **Prototyping:** Used as a user-configurable input for microcontrollers (e.g., selecting between 16 different operation modes using 4 bits). --- ### 4. Typical Connection Diagram In most digital circuits, one side of the switch is connected to Ground (GND), and the other side is connected to a Microcontroller (MCU) pin with an internal or external pull-up resistor. ```c // Example Logical State Table for 4-position Switch // Switch Position | Binary Value | Hex Value // ----------------|--------------|---------- // OFF-OFF-OFF-OFF | 0000 | 0x0 // ON -OFF-OFF-OFF | 0001 | 0x1 // ON -ON -ON -ON | 1111 | 0xF ```