The **M7S28FCJ-R** is a high-performance, surface-mount oscillator, typically categorized as a **TCXO (Temperature Compensated Crystal Oscillator)** or a high-stability clock source manufactured by suppliers like **Mercury Electronic**. Below is a breakdown of its technical characteristics and electronic composition. --- ### 1. General Specifications The part number follows a specific nomenclature related to its physical size, stability, and output type. | Feature | Specification (Typical) | | :--- | :--- | | **Component Type** | Temperature Compensated Crystal Oscillator (TCXO) | | **Package Size** | 7.0 x 5.0 mm (SMD Package) | | **Output Type** | CMOS / Reduced Sine Wave (variant dependent) | | **Supply Voltage** | Usually 2.5V, 3.0V, or 3.3V | | **Frequency Stability** | ±0.5ppm to ±2.5ppm (Temperature dependent) | | **Operating Temp** | -40°C to +85°C (Industrial Grade) | --- ### 2. Internal Electronic Structure The "M7S" series integrates several electronic layers into a single ceramic package: 1. **AT-Cut Quartz Crystal:** The primary resonating element providing the base frequency. 2. **Compensation IC:** A specialized integrated circuit that senses the ambient temperature and adjusts the load capacitance to keep the frequency stable. 3. **Varactor Diode:** Used within the compensation circuit to "pull" the frequency back to its nominal value as temperatures change. 4. **Voltage Regulator:** Internal circuitry to ensure that fluctuations in the input supply voltage do not cause "pushing" (frequency shifts). --- ### 3. Pin Configuration (4-Pad Layout) Standard for the 7050 (7x5mm) footprint used by the M7S series: | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | Vcon / NC | Voltage Control (for VCTCXO) or No Connection | | **2** | GND | Ground / Case Connection | | **3** | Output | Frequency Output Signal | | **4** | Vdd | DC Power Supply Input | --- ### 4. Key Applications Because of its high stability and compact SMD form factor, this part is used in: * **Telecommunications:** Base stations and small cells. * **GPS/GNSS Receivers:** Providing a stable clock for satellite signal acquisition. * **Networking:** Synchronous Ethernet and high-speed routers. * **IoT Devices:** Low-power wide-area network (LPWAN) modules. ---