The part number **I641-33AB3O2-155.520** refers to a high-precision **Voltage Controlled Crystal Oscillator (VCXO)**. These components are critical in telecommunications and data processing for clock synchronization and frequency control. ### Component Breakdown The alphanumeric code follows a specific naming convention used by manufacturers (typically Ilsi or similar timing component specialists). | Section | Value | Description | | :--- | :--- | :--- | | **Series** | I641 | High-stability SMD VCXO (typically 5x7mm package) | | **Operating Voltage** | 33 | **3.3V** DC Power Supply | | **Output Type** | A | **LVPECL** (Low-Voltage Positive Emitter-Coupled Logic) | | **Frequency Stability** | B | Usually signifies **±50 ppm** stability | | **Temp Range** | 3 | Operating range of **-40°C to +85°C** (Industrial Grade) | | **Pullability** | O2 | Minimum pull range (e.g., ±100 ppm) for frequency tuning | | **Frequency** | 155.520 | **155.520 MHz** (Standard SONET/SDH frequency) | --- ### Key Technical Specifications #### 1. Frequency (155.520 MHz) This is a standard frequency used in **SONET (OC-3)** and **SDH (STM-1)** optical networking equipment. It is derived from the base transmission rate for high-speed fiber-optic communication. #### 2. Output Logic: LVPECL * **Performance:** High speed with very low jitter. * **Structure:** Differential output, which provides excellent noise immunity compared to single-ended signals (like CMOS). #### 3. Voltage Control (VCXO Function) Unlike a standard fixed oscillator, this part has a "Control Voltage" pin. By changing the input voltage on this pin, the user can slightly "pull" or adjust the output frequency. This is essential for **Phase-Locked Loops (PLLs)** to lock onto an external reference clock. #### 4. Physical Characteristics * **Package Size:** Most I641 series parts utilize a 6-pad **5.0 x 7.0 mm** ceramic Surface Mount Device (SMD) package. * **Reliability:** Designed for industrial environments with high resistance to shock and vibration. --- ### Common Applications * **Optical Networking:** SONET/SDH, Gigabit Ethernet. * **Base Stations:** Synchronizing timing in cellular infrastructure. * **Test & Measurement:** High-speed digitized systems requiring low-jitter clock sources. * **Clock Recovery:** Used in circuits that extract timing information from data streams.