The **SMS-1508-2-R** is a high-performance, miniature surface-mount (SMT) loudspeaker manufactured by **PUI Audio**. It is specifically designed for applications where space is at a premium, but clear sound reproduction is required. --- ## 1. Technical Specifications The following table summarizes the core electronic and physical characteristics of the component: | Feature | Specification | | :--- | :--- | | **Type** | Dynamic Speaker (Moving Coil) | | **Rated Power** | 0.5 Watts | | **Maximum Power** | 0.8 Watts | | **Impedance** | 8 Ohms ± 15% | | **Sound Pressure Level (SPL)** | 85 dB ± 3dB @ 0.1W / 0.1M | | **Resonant Frequency (Fo)** | 850 Hz ± 20% | | **Frequency Range** | 850 Hz ~ 20,000 Hz | | **Mounting Type** | Surface Mount (SMT) | | **Dimensions** | 15mm x 8mm x 2.5mm | --- ## 2. Internal Electronic Construction The device operates on standard electromagnetic principles but is scaled down to a micro-form factor: * **Voice Coil:** A fine copper wire coil attached to the diaphragm. When an AC signal passes through, it creates a fluctuating magnetic field. * **Permanent Magnet:** Typically a Neodymium (NdFeB) magnet, which provides a high magnetic flux density relative to its small size. * **Diaphragm:** Made from a lightweight polymer (often PEEK or similar), which vibrates to move air and create sound waves. * **Frame:** A high-temperature plastic housing designed to withstand the heat of lead-free reflow soldering processes. --- ## 3. Key Electronic Considerations ### Drive Signal To drive the SMS-1508-2-R, you typically need a small **Class-D or Class-AB audio amplifier**. Because the impedance is **8 Ohms**, it is compatible with most standard low-power audio ICs. ### Polarity and Protection * **Polarity:** The device has specific SMT pads for positive (+) and negative (-). Maintaining correct polarity is crucial in multi-speaker setups to prevent phase cancellation. * **DC Blocking:** It is recommended to use a **DC blocking capacitor** in series with the speaker if the amplifier output has a DC offset, as DC current will cause the voice coil to overheat and fail. ### Thermal Management As an SMT component, the speaker relies on the PCB traces to help dissipate a small amount of heat. However, since it is rated at 0.5W, it is vital not to exceed the **0.8W peak** limit to prevent the voice coil from melting or the adhesive holding the diaphragm from failing. --- ## 4. Typical Applications * Handheld medical devices. * IoT sensors and smart home hubs. * Portable scanners and POS terminals. * Wearable electronics.