The part number **I640-31AC8O2-155.520** refers to a high-precision **Voltage Controlled Crystal Oscillator (VCXO)**, typically manufactured by companies specializing in timing components like *ILSI America* (now part of Ecliptek/Abracon). Below is the detailed breakdown of its electronic specifications and nomenclature. ### 1. General Specifications This component is designed for high-speed networking and telecommunications equipment that requires stable clock signals. | Feature | Specification | | :--- | :--- | | **Component Type** | VCXO (Voltage Controlled Crystal Oscillator) | | **Frequency** | 155.520 MHz | | **Output Type** | LVPECL (Low-Voltage Positive Emitter-Coupled Logic) | | **Supply Voltage** | 3.3V DC | | **Package Size** | 5.0mm x 7.0mm (Standard 6-pad SMD) | --- ### 2. Part Number Decoder The alphanumeric string defines the specific electrical characteristics of the oscillator: | Segment | Meaning | Description | | :--- | :--- | :--- | | **I640** | Series/Model | Represents the 5x7mm surface mount VCXO series. | | **31** | Operating Voltage | Typically indicates **3.3V** supply voltage. | | **A** | Frequency Stability | Usually represents **±50ppm** or **±25ppm** (Check datasheet for specific grade). | | **C** | Operating Temp | **0°C to +70°C** (Commercial Temperature Range). | | **8** | Pulling Range | Indicates the minimum control range (e.g., **±80ppm** to **±100ppm**). | | **O2** | Output Logic | Specifies **LVPECL** differential output. | | **155.520** | Nominal Frequency | **155.520 MHz** (Standard frequency for OC-3/STM-1 SONET/SDH). | --- ### 3. Key Electronic Characteristics * **LVPECL Output:** This is a differential signaling standard. It provides high-speed performance with low jitter, making it ideal for fiber optic systems and high-speed backplanes. * **Voltage Control (V_c):** Unlike a standard crystal, a VCXO allows the output frequency to be "tuned" or adjusted slightly by applying an external analog voltage to Pin 1. * **155.520 MHz Frequency:** This specific frequency is a fundamental building block for **SONET/SDH** telecommunication networks, specifically used in OC-3 and STM-1 transmission rates. ### 4. Typical Applications * **Optical Networking:** SONET/SDH, Gigabit Ethernet. * **Phase Locked Loops (PLL):** Used as a local oscillator that can be synchronized to a reference clock. * **Broadband Access:** Data distribution and base station synchronization. ---