The **BPA09-R-S-B-R** is a specific model of a DIP (Dual In-line Package) switch, typically manufactured by companies like **C&K** (now part of Littelfuse). These components are widely used on printed circuit boards (PCBs) to manually set configuration parameters or logic levels. ### 1. Part Number Breakdown (Nomenclature) The alphanumeric code provides specific details about the component's physical and electrical properties: | Segment | Meaning | Description | | :--- | :--- | :--- | | **BPA** | Series Name | Standard Side Actuated DIP Switch Series | | **09** | Number of Positions | Indicates this unit has **9 individual switches** | | **R** | Actuator Style | **Recessed Actuator** (flush with the housing) | | **S** | Terminals | **Solder Pad / Surface Mount (SMT)** terminals | | **B** | Contact Material | **Gold over Nickel** (provides high reliability) | | **R** | Packaging | **Tape & Reel** (standard for automated pick-and-place) | --- ### 2. Technical Specifications The electrical and mechanical characteristics define how the switch operates within a circuit: * **Switch Type:** SPST (Single Pole Single Throw). * **Contact Rating:** * *Non-Switching:* 100 mA @ 50 V DC. * *Switching:* 100 mA @ 5 V DC or 25 mA @ 24 V DC. * **Contact Resistance:** Max 50 mΩ initially. * **Insulation Resistance:** 100 MΩ minimum at 500 V DC. * **Operating Temperature:** -20°C to +85°C. * **Mechanical Life:** Typically 1,000 cycles per switch. --- ### 3. Key Physical Features 1. **Side Actuation:** Unlike top-actuated switches, these are toggled from the side. This is ideal for boards stacked closely together or when the switch needs to be accessible from the edge of an enclosure. 2. **Bifurcated Contacts:** The internal contact mechanism often uses a "twin" contact design to ensure a stable electrical connection even if there is slight debris or oxidation. 3. **Process Sealed:** Most variants in this series are designed to withstand wave soldering and aqueous cleaning processes (check the specific datasheet for the "tape seal" option). --- ### 4. Common Applications * **Address Settings:** Setting the binary address for a device on a network (e.g., RS-485 or DMX). * **Logic Configuration:** Enabling/disabling specific hardware features on a PCB without reprogramming firmware. * **Industrial Controls:** Setting timers, sensor thresholds, or operational modes in PLC peripherals. ---