The **LSMT2-34540-R** is a high-performance, surface-mount (SMT) magnetic buzzer/transducer designed by **Leadway**. It is widely used in portable electronics, medical devices, and security systems due to its compact size and high sound pressure output. --- ## 🟢 Technical Specifications Below are the primary electronic and physical characteristics for the LSMT2-34540-R: | Parameter | Value / Specification | | :--- | :--- | | **Part Number** | LSMT2-34540-R | | **Rated Voltage** | 3.6 Vp-p | | **Operating Voltage** | 2.5 ~ 4.5 Vp-p | | **Rated Current** | Max 100 mA | | **Resonant Frequency** | 2,730 Hz | | **Sound Pressure Level (SPL)** | Min 87 dB (at 10cm, Rated Voltage) | | **Coil Resistance** | 16 ± 3 Ω | | **Operating Temperature** | -30°C to +70°C | | **Dimensions** | 9.0 x 9.0 x 4.0 mm | --- ## 🛠️ Internal Electronic Structure The device functions as a **Magnetic Transducer**. Unlike a "self-driven" buzzer that makes sound as soon as DC voltage is applied, this component requires an **external drive circuit** (an oscillating signal). ### 1. Coil and Core The heart of the part is a copper coil wrapped around a magnetic core. When an AC signal or PWM (Pulse Width Modulation) signal passes through the coil, it generates a fluctuating magnetic field. ### 2. The Diaphragm A thin metal disk (diaphragm) sits above the magnet. The magnetic fluctuations cause the diaphragm to vibrate at the frequency of the input signal, creating sound waves. ### 3. SMT Terminals The "-R" suffix usually denotes "RoHS Compliant." The pads are designed for reflow soldering on a PCB (Printed Circuit Board). --- ## 🔌 Typical Drive Circuit To operate this part, you generally use a transistor to switch the current through the coil, as microcontrollers usually cannot provide the required 100mA directly. ```c // Example Pseudocode for driving the LSMT2-34540-R with an Arduino/MCU void setup() { pinMode(BUZZER_PIN, OUTPUT); } void loop() { // Generate a 2730Hz square wave for maximum efficiency tone(BUZZER_PIN, 2730); delay(500); noTone(BUZZER_PIN); delay(500); } ``` --- ## ⚠️ Design Considerations * **Polarity:** As a magnetic transducer, it is polarized. Ensure the "+" mark on the casing aligns with the positive side of your drive circuit. * **Flyback Diode:** Since the device is inductive (contains a coil), it is recommended to place a diode in parallel with the buzzer to protect your driving transistor from voltage spikes when the current is switched off. * **Resonant Frequency:** To achieve the rated 87dB sound level, the input frequency must be kept as close to **2,730 Hz** as possible. Deviation from this frequency will result in a significantly quieter sound.