The part number **I640-63BC3O2-155.520** refers to a high-precision **Voltage Controlled Crystal Oscillator (VCXO)**, typically manufactured by ILSI America (now part of the Abracon group). These components are critical for frequency control in high-speed telecommunications and networking hardware. --- ### 1. Part Number Breakdown The nomenclature follows a specific coding structure that defines the electrical and physical characteristics of the device: | Segment | Value | Description | | :--- | :--- | :--- | | **Series** | I640 | 5.0 x 7.0 mm Surface Mount (SMD) VCXO | | **Voltage** | 6 | +3.3 VDC Operating Voltage | | **Output** | 3 | LVPECL (Low-Voltage Positive Emitter-Coupled Logic) | | **Stability** | B | ±50 ppm Stability | | **Temp Range** | C | -20°C to +70°C (Commercial Grade) | | **Pullability** | 3 | ±100 ppm Minimum Pull Range | | **Duty Cycle** | O | 45/55% Symmetry | | **Tri-state** | 2 | Enable/Disable Function on Pin 2 | | **Frequency** | 155.520 | 155.520 MHz (Standard SDH/SONET Frequency) | --- ### 2. Key Technical Specifications Based on the decoded string, the electronic behavior of this part is characterized by: * **Frequency:** 155.520 MHz. This is a standard frequency used in **OC-3/STM-1** optical networking protocols. * **Logic Type (LVPECL):** This differential signaling method is used for high-frequency applications because it provides excellent noise immunity and very fast switching speeds (low jitter). * **Pullability:** The "Pull Range" of ±100 ppm allows the output frequency to be adjusted slightly by varying the control voltage. This is essential for Phase-Locked Loops (PLL) to synchronize with an incoming data stream. * **Package Size:** 7.0 x 5.0 mm with 6 pads, designed for automated SMT (Surface Mount Technology) assembly. --- ### 3. Common Applications This specific component is usually found in the following electronic systems: 1. **Telecommunications:** SDH (Synchronous Digital Hierarchy) and SONET (Synchronous Optical Networking) equipment. 2. **Data Communications:** Gigabit Ethernet and Fiber Channel switches. 3. **Clock Recovery:** Used in circuits that need to "lock" onto a specific timing signal from a network provider. 4. **Base Stations:** Cellular infrastructure requiring precise timing for synchronization. --- ### 4. Typical Connection Diagram (6-Pad Layout) | Pad Number | Function | Description | | :--- | :--- | :--- | | 1 | Vc | Control Voltage (Input to adjust frequency) | | 2 | E/D or NC | Enable/Disable (Tri-state) | | 3 | GND | Case Ground | | 4 | Output | LVPECL Output | | 5 | Comp Output | Complementary LVPECL Output | | 6 | Vdd | Supply Voltage (+3.3V) |