The part number **I640-31AC3O2-155.520** refers to a high-precision **Voltage Controlled Crystal Oscillator (VCXO)**. These components are critical in telecommunications and high-speed data networking for frequency synchronization. --- ### 1. Technical Specification Breakdown The alphanumeric string follows a specific coding convention used by manufacturers like *ILSI* or *MtronPTI*. Here is the breakdown of the technical characteristics: | Code Segment | Parameter | Description | |:---|:---|:---| | **I640** | Series/Package | Typically a 5x7 mm Surface Mount Device (SMD) package. | | **3** | Operating Voltage | **3.3V DC** supply voltage. | | **1** | Stability | Frequency stability (often ±50ppm or ±25ppm, depending on chart). | | **AC** | Temp Range | Commercial or Industrial range (usually -20°C to +70°C). | | **3** | Output Type | **LVPECL** (Low-Voltage Positive Emitter-Coupled Logic). | | **O2** | Pullability | Voltage control range (typically ±50ppm to ±100ppm). | | **155.520** | Frequency | **155.520 MHz** (The fundamental frequency). | --- ### 2. Key Electronic Features #### Frequency: 155.520 MHz This is a standard telecommunications frequency. It is the base clock for **SONET/SDH** (Synchronous Optical Networking) protocols, specifically **OC-3 / STM-1**. #### Output Logic: LVPECL * **Speed:** Very fast switching speeds suitable for high-frequency applications. * **Noise:** Differential signaling provides excellent common-mode noise rejection. * **Power:** Consumes more power than CMOS but offers superior jitter performance. #### VCXO Functionality Unlike a fixed crystal, this component has a **Control Voltage (Vc)** pin. By varying the voltage on this pin, the output frequency can be "pulled" or tuned slightly. This is essential for: * Phase-Locked Loops (PLLs). * Clock and Data Recovery (CDR). * Synchronizing local clocks to a master reference. --- ### 3. Application Use Cases * **Optical Networking:** SFP/SFP+ transceiver modules and line cards. * **Broadband Access:** Digital Subscriber Line Access Multiplexers (DSLAM). * **Test Equipment:** High-speed signal generators and oscilloscopes. * **Base Stations:** Cellular infrastructure requiring precise timing for data packets. --- ### 4. Implementation Schematic (Simplified) ```mermaid graph LR Vcc[3.3V Power] --> Part(I640-31AC3O2) GND[Ground] --> Part CtrlV[Control Voltage 0-3.3V] --> Part Part --> Out+[PECL Output +] Part --> Out-[PECL Output -] ```