The **SMA15VG-CB2-R** is a high-performance, surface-mount (SMD) piezoelectric buzzer (transducer) typically manufactured by companies like **Challenge Electronics**. It is designed for applications requiring high sound pressure levels (SPL) in a compact, low-profile package. Below is a detailed breakdown of its electronic specifications and features. --- ## 1. Technical Specifications The following table outlines the primary electrical and physical characteristics of the SMA15VG-CB2-R: | Parameter | Value | | :--- | :--- | | **Type** | Piezoelectric Transducer (External Drive) | | **Operating Voltage** | 3.0 ~ 20.0 Vp-p | | **Rated Voltage** | 5.0 Vp-p (Square Wave) | | **Current Consumption** | $\le$ 5 mA (at rated voltage) | | **Sound Pressure Level (SPL)** | $\ge$ 80 dB (at 10cm / 5Vp-p / 4kHz) | | **Resonant Frequency** | 4,000 Hz $\pm$ 500 Hz | | **Capacitance** | 12,000 pF $\pm$ 30% (at 120Hz) | | **Operating Temperature** | -40°C to +85°C | | **Mounting Type** | Surface Mount (SMD) | --- ## 2. Component Composition This part consists of several key electronic and mechanical elements: ### A. Piezoelectric Ceramic Element The "heart" of the device is a lead zirconate titanate (PZT) ceramic disk. When an alternating voltage is applied, the inverse piezoelectric effect causes the disk to deform physically, vibrating the air to create sound. ### B. Internal Housing The **"CB2"** in the part number often refers to the specific housing design. It utilizes a Liquid Crystal Polymer (LCP) or similar high-temperature plastic case, allowing it to withstand the heat of lead-free reflow soldering processes. ### C. Electrical Terminals The device features brass or copper alloy leads with tin plating for SMD soldering. As a **transducer** (rather than an indicator), it does not have internal circuitry to generate a tone; it requires an external oscillating signal. --- ## 3. Implementation and Driving Circuit Because this is an **External Drive** transducer, you cannot simply apply a DC voltage to it. You must provide a square wave at its resonant frequency (4.0 kHz). ### Example Drive Circuit A simple BJT or MOSFET switching circuit is typically used to drive the piezo: ```text VCC (3-20V) | +----------+ | | [Piezo] [Diode/Resistor for | Back-EMF Protection] | | (C/D) + | [NPN/N-CH] <--- PWM Signal (4kHz) | GND ``` --- ## 4. Key Advantages * **Low Current Draw:** Unlike magnetic buzzers, piezo transducers consume very little power, making them ideal for battery-operated devices. * **Thin Profile:** Its "VG" designation usually refers to a "Vertical" or specific low-height geometry suitable for slim electronics like handheld meters or medical devices. * **Durability:** No moving mechanical contacts (like an electromagnetic clapper), leading to a longer lifespan.