The **LSMT2-11550-R** is a high-performance, surface-mount (SMT) magnetic transducer (buzzer) commonly used in consumer electronics, medical devices, and security systems. It is designed to provide audible feedback while maintaining a compact footprint. --- ### 1. Key Technical Specifications Below are the primary electrical and physical characteristics of the component: | Parameter | Specification | | :--- | :--- | | **Type** | Magnetic Transducer (Requires external drive) | | **Rated Voltage** | 5.0 Vo-p | | **Operating Voltage** | 3.0 ~ 7.0 Vo-p | | **Rated Current** | Max 80 mA | | **Sound Pressure Level (SPL)** | Min 85 dB (at 10cm) | | **Resonant Frequency** | 2400 Hz | | **Coil Resistance** | 40 ± 6 Ω | | **Mounting Type** | Surface Mount (SMD) | | **Dimensions** | ~11.0 x 11.0 x 5.0 mm | --- ### 2. Functional Components The LSMT2-11550-R consists of several internal electronic and mechanical parts: 1. **Coil:** A copper winding that creates an electromagnetic field when an oscillating current passes through it. 2. **Permanent Magnet:** Provides a static magnetic field that interacts with the coil's field. 3. **Vibrating Diaphragm:** A metal disk that moves rapidly in response to magnetic fluctuations, pushing air to create sound waves. 4. **Housing (LCP/Plastic):** High-temperature resistant material designed to survive reflow soldering processes. 5. **SMD Terminals:** Gold-plated or tin-plated pads for soldering directly onto a PCB. --- ### 3. Driving Circuit Requirements Unlike an "indicator" (which makes sound just by applying DC), the LSMT2-11550-R is a **transducer**. It requires an external AC signal or a switched DC signal at its resonant frequency (2400 Hz) to function. #### Recommended Driver Circuit To protect your microcontroller and ensure maximum volume, a transistor-driven circuit is typically used: ```cpp // Example: Driving logic for a Microcontroller (Arduino/ESP32) // Connect the buzzer through a NPN transistor (like S8050) void setup() { pinMode(BUZZER_PIN, OUTPUT); } void loop() { tone(BUZZER_PIN, 2400); // Send square wave at resonant frequency delay(500); noTone(BUZZER_PIN); delay(500); } ``` --- ### 4. Application Considerations * **Polarity:** Observe the "+" marking on the casing to ensure correct phase and performance. * **Washability:** Most versions are not sealed; ensure you do not wash the PCB with the buzzer attached unless it has a protective "wash label." * **Reflow Soldering:** Follow the JEDEC heat profile to avoid melting the internal components or de-magnetizing the permanent magnet.