## Detailed Technical Overview: APTE-5121-R The **APTE-5121-R** is a high-performance, surface-mount (SMD) piezoelectric transducer (buzzer) commonly used in consumer electronics for audible feedback. It is designed to provide clear sound output while maintaining a small footprint. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Type** | Piezoelectric Transducer (External Drive) | | **Rated Voltage** | 3.0 Vp-p | | **Operating Voltage Range** | 1.0 ~ 20.0 Vp-p | | **Resonant Frequency** | 4,000 ± 500 Hz | | **Sound Pressure Level (SPL)** | ≥ 75 dB (at 10cm, 3Vp-p, 4kHz) | | **Current Consumption** | ≤ 3 mA | | **Capacitance** | 12,000 pF ± 30% (at 120Hz) | | **Mounting Type** | Surface Mount (SMD) | | **Operating Temperature** | -40°C to +85°C | --- ### 2. Functional Components * **Piezoelectric Ceramic Element:** The core of the device. When an alternating voltage is applied, the ceramic expands and contracts (the inverse piezoelectric effect), vibrating the attached metal plate to create sound waves. * **Vibrating Plate:** Usually made of brass or stainless steel, this plate amplifies the vibrations of the ceramic element. * **Housing/Casing:** A Liquid Crystal Polymer (LCP) or high-temperature plastic shell that protects the internal components and provides an acoustic chamber to tune the frequency. * **Contact Terminals:** Solder pads designed for SMT (Surface Mount Technology) assembly, allowing for automated pick-and-place manufacturing. --- ### 3. Circuit Integration Requirements Because the APTE-5121-R is a **transducer** (not an indicator), it does not have internal oscillation circuitry. To produce sound, the engineer must provide an external square wave signal. #### Driving Circuit Example A common way to drive this component is using a simple NPN transistor or a MOSFET controlled by a Microcontroller (MCU) PWM pin. ```c // Example Pseudocode for driving the buzzer void play_tone(int frequency, int duration_ms) { pwm_set_frequency(frequency); // Target 4000Hz for peak volume pwm_start(); delay(duration_ms); pwm_stop(); } ``` --- ### 4. Application Use Cases * **Handheld Devices:** Beeps for button presses or error alerts. * **Medical Instrumentation:** Low-power alarms for portable monitors. * **Automotive:** Dashboard alerts and proximity sensor feedback. * **IoT Devices:** Status notifications for smart home sensors. --- ### 5. Mechanical Dimensions (Typical) * **Length/Width:** Approx. 5.0mm x 5.0mm * **Height:** Approx. 2.0mm to 2.5mm * **Weight:** Extremely lightweight (approx. 0.1g), making it ideal for vibration-sensitive assemblies.