The part number **I641-63BC3O2-155.520** refers to a high-precision **Voltage Controlled Crystal Oscillator (VCXO)**, typically manufactured by companies like ILSI (now part of Abracon) or similar frequency control specialists. --- ### 1. Part Number Breakdown Based on standard industry nomenclature for the I641 series, here is the technical breakdown of the code: | Segment | Code | Description | | :--- | :--- | :--- | | **Series** | `I641` | VCXO, 5.0 x 3.2 mm Surface Mount Device (SMD). | | **Supply Voltage** | `6` | Typically indicates **3.3V DC** operation. | | **Output Type** | `3` | **LVPECL** (Low-Voltage Positive Emitter-Coupled Logic). | | **Stability** | `B` | Frequency Stability (often ±50ppm or ±25ppm depending on the datasheet). | | **Temp Range** | `C` | Operating Temperature, usually **-20°C to +70°C**. | | **Pullability** | `3O2` | Pull range specification (e.g., ±100ppm or similar). | | **Frequency** | `155.520` | Operating frequency of **155.520 MHz**. | --- ### 2. Key Technical Specifications This component is designed for high-speed telecommunications. * **Frequency:** 155.520 MHz (Standard frequency for OC-3/STM-1 SONET/SDH networks). * **Package Size:** 5.0mm x 3.2mm (6-pad ceramic package). * **Logic Output:** LVPECL. This provides high-speed switching with low jitter, ideal for clock distribution. * **Control Voltage:** Allows the frequency to be adjusted (pulled) by varying the input voltage on Pin 1. * **Phase Jitter:** Extremely low (sub-picosecond), necessary for high-speed data integrity. --- ### 3. Common Applications Due to the specific frequency and output logic, this part is used in: 1. **Optical Networking:** SONET, SDH, and Synchronous Ethernet (SyncE). 2. **Base Stations:** Cellular infrastructure requiring precise timing synchronization. 3. **Test Equipment:** High-speed digital oscilloscopes and signal generators. 4. **Phase-Locked Loops (PLLs):** Used as the tunable element in a frequency synthesis circuit. --- ### 4. Typical Pin Configuration Most 5x3.2mm VCXOs follow this standard 6-pad layout: | Pin | Function | Description | | :--- | :--- | :--- | | 1 | Vc | Control Voltage (Input to adjust frequency). | | 2 | E/D | Enable/Disable (Tri-state function). | | 3 | GND | Case Ground. | | 4 | Output | Main Clock Output. | | 5 | Output Comp | Complementary Clock Output (Differential). | | 6 | Vdd | Supply Voltage (+3.3V). |