## Detailed Overview: SMS-1308MS-R The **SMS-1308MS-R** is a high-performance, surface-mount (SMT) miniature speaker manufactured by **PUI Audio**. It is primarily designed for compact electronic devices where space is limited but clear audio output is required. --- ### 1. Technical Specifications The following table outlines the key electrical and physical characteristics of the component: | Parameter | Specification | | :--- | :--- | | **Type** | Dynamic Speaker (Moving Coil) | | **Rated Power** | 0.7 Watts | | **Maximum Power** | 1.0 Watts | | **Impedance** | 8 Ohms ± 15% | | **Sound Pressure Level (SPL)** | 89 dB ± 3dB @ 0.7W / 0.1M | | **Resonant Frequency (Fo)** | 850 Hz ± 20% | | **Frequency Range** | 850 Hz ~ 20,000 Hz | | **Dimensions** | 13mm x 8mm x 2.5mm | | **Mounting Type** | Surface Mount (SMT) | --- ### 2. Key Features and Materials The SMS-1308MS-R is engineered for durability and automated manufacturing: * **Construction:** * **Diaphragm:** Typically made of Mylar (PET) for moisture resistance and crisp sound. * **Magnet:** Uses Neodymium (NdFeB), which provides a strong magnetic field in a small footprint. * **Reflow Solderable:** Designed to withstand the high temperatures of infrared reflow ovens, making it ideal for mass production. * **Side-Firing Design:** The sound exits from the side (lateral), allowing for thinner device profiles. * **RoHS Compliant:** Free from lead and other hazardous substances. --- ### 3. Application Use Cases Due to its small form factor and SMT design, it is commonly found in: 1. **Handheld Medical Devices:** For audible alerts and heart rate monitoring beeps. 2. **IoT Devices:** Smart home sensors that require voice feedback or alarm tones. 3. **Wearables:** Fitness trackers or smartwatches with limited internal volume. 4. **Security Hardware:** Keypads and card readers for entry confirmation tones. --- ### 4. Integration Considerations When designing a PCB for this part, keep the following in mind: * **Acoustic Chamber:** To maximize the 89dB SPL, a properly sized back-cavity (enclosure) is recommended to prevent front-to-back wave cancellation. * **Polarity:** Ensure the positive (+) and negative (-) terminals are correctly oriented as per the datasheet to maintain phase alignment in multi-speaker setups. * **Drive Circuit:** It can be driven directly by a small Class-D audio amplifier or even a microcontroller PWM pin (with a decoupling capacitor and current-limiting resistor), though a dedicated amp is preferred for sound quality.