The **LSMT2-34560-R** is a high-performance, surface-mount (SMT) magnetic buzzer/transducer designed for applications requiring a compact footprint and high sound pressure levels. It is commonly used in portable electronics, medical devices, and automotive dash systems. --- ### 1. Key Technical Specifications Below are the typical electronic and physical parameters for this component: | Parameter | Specification | | :--- | :--- | | **Rated Voltage** | 3.0 Vp-p | | **Operating Voltage** | 2.0 ~ 5.0 Vp-p | | **Rated Current** | Max. 90 mA | | **Sound Pressure Level (SPL)** | Min. 85 dB (at 10cm) | | **Resonant Frequency** | 2,700 Hz | | **Coil Resistance** | 18 ± 3 Ω | | **Operating Temperature** | -40°C to +85°C | | **Mounting Type** | Surface Mount (SMT) | --- ### 2. Internal Electronic Structure The LSMT2-34560-R operates on **Electromagnetic Induction** principles. Unlike piezo buzzers (which act like capacitors), this is a magnetic transducer: * **Voice Coil:** A small coil of wire with a nominal resistance of roughly 18 Ohms. When current passes through, it creates a magnetic field. * **Permanent Magnet:** Provides a stationary magnetic field that interacts with the coil's field. * **Vibrating Diaphragm:** A metal disk that is pulled and released by the fluctuating magnetic field, creating sound waves. * **Driving Circuitry:** Because this is a **transducer** (not an indicator), it requires an external oscillating signal (square wave) at its resonant frequency (2700Hz) to produce sound. --- ### 3. Application Circuit Design To drive this component effectively, a transistor switching circuit is recommended to handle the ~90mA current draw, as most microcontroller pins cannot provide that much current directly. ```c // Typical Drive Logic 1. Set MCU Pin as PWM Output. 2. Frequency = 2700 Hz (Resonant Frequency). 3. Duty Cycle = 50% for maximum volume. ``` #### Basic Schematic Layout: 1. **VCC (3V/5V)** connected to the positive terminal of the buzzer. 2. **Negative Terminal** connected to the **Collector** of an NPN transistor (e.g., S8050). 3. **Emitter** connected to Ground. 4. **Base** connected to the MCU via a 1kΩ resistor. 5. **Flyback Diode:** A diode should be placed in parallel with the buzzer (cathode to VCC) to protect the transistor from inductive voltage spikes. --- ### 4. Handling & Soldering * **Reflow Soldering:** Designed to withstand standard lead-free reflow profiles. * **Washability:** Usually "non-washable" unless specified with a top-side label/seal. If it is not sealed, aqueous cleaning can damage the internal diaphragm.