The **LSMT2-10540-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 clear acoustic feedback while maintaining a small PCB footprint. ### 1. Key Technical Specifications The following table outlines the core electronic and physical characteristics of the component: | Feature | Specification | | :--- | :--- | | **Type** | Magnetic Transducer (External Drive) | | **Rated Voltage** | 3.6 Vp-p | | **Operating Voltage** | 2.5 ~ 4.5 Vp-p | | **Rated Current** | Max 100 mA | | **Sound Pressure Level (SPL)** | Min 87 dB (at 10cm) | | **Resonant Frequency** | 2700 Hz | | **Coil Resistance** | 15 ± 3 Ω | | **Operating Temperature** | -40°C to +85°C | | **Mounting Type** | Surface Mount (SMT) | --- ### 2. Functional Description #### A. Transducer Type: External Drive Unlike an "indicator" (which has internal circuitry to produce sound when DC is applied), the LSMT2-10540-R is a **transducer**. It requires an external oscillating signal (Square Wave) at its resonant frequency (2700 Hz) to produce sound. #### B. Magnetic Mechanism The device consists of a permanent magnet, a copper coil, and a metal diaphragm. When an alternating current passes through the coil, it creates a fluctuating magnetic field that moves the diaphragm, generating sound waves. #### C. Side-Firing Design The "10540" naming convention often refers to its dimensions (approx. 10x10x4mm). These units are frequently designed as "side-port" or "side-firing," meaning the sound exits from the side of the housing rather than the top, allowing for lower-profile product designs. --- ### 3. Application Circuit Example To drive this part using a microcontroller (MCU), a simple transistor switching circuit is required to handle the current requirements (up to 100mA), which exceeds the GPIO limit of most MCUs. ```c // Example Pseudocode for 2700Hz Tone Generation void playBuzzer() { // Frequency = 2700Hz -> Period = 370 microseconds // Half Period = 185 microseconds while(alarm_active) { digitalWrite(BUZZER_PIN, HIGH); delayMicroseconds(185); digitalWrite(BUZZER_PIN, LOW); delayMicroseconds(185); } } ``` --- ### 4. Comparison: Transducer vs. Indicator | Feature | LSMT2-10540-R (Transducer) | Active Indicator (Buzzer) | | :--- | :--- | :--- | | **Input** | AC / Square Wave | DC Voltage | | **Flexibility** | Can change pitch/frequency | Fixed frequency | | **Circuitry** | Requires external oscillator | Internal oscillator included | | **Complexity** | Higher | Lower |