The part number **I641-61AB8O2-155.520** refers to a high-precision, low-jitter frequency control component, specifically a **Voltage Controlled Crystal Oscillator (VCXO)** or a standard **Crystal Oscillator (XO)** produced by ILSI (a brand under Abracon). Below is the technical breakdown of the component's specifications based on standard industry coding for this series. --- ### 1. Technical Specification Table | Feature | Detail | Description | | :--- | :--- | :--- | | **Primary Category** | Frequency Control | Crystal Oscillator (SMD) | | **Frequency** | 155.520 MHz | Standard frequency for SONET/SDH/ATM networks | | **Output Type** | LVPECL / LVDS | Differential signaling for high-speed data | | **Supply Voltage** | 3.3V or 2.5V | Common logic supply voltage | | **Package Size** | 5.0 x 7.0 mm | 6-pad Ceramic Surface Mount Device (SMD) | | **Stability** | ±20ppm to ±50ppm | Variation over temperature range | | **Operating Temp** | -40°C to +85°C | Industrial temperature grade | --- ### 2. Part Number Breakdown The alphanumeric string describes the physical and electrical characteristics: 1. **I641**: Represents the series (typically a 5x7mm 6-pad differential output oscillator). 2. **61**: Internal code for specific electrical characteristics (Supply voltage/Output type). 3. **A**: Operating temperature range (typically Industrial: -40°C to +85°C). 4. **B**: Frequency stability code (e.g., ±50ppm). 5. **8O2**: Specific internal configuration or revision code. 6. **155.520**: The output frequency in Megahertz (MHz). --- ### 3. Key Electronic Characteristics #### A. Differential Output (LVPECL/LVDS) At 155.520 MHz, signal integrity is critical. This part likely uses **Low-Voltage Positive Emitter-Coupled Logic (LVPECL)**. This provides high-speed switching, low phase noise, and excellent jitter performance, which is necessary for high-speed clocking. #### B. Frequency Significance (155.520 MHz) This specific frequency is the "Golden Frequency" for **Optical Networking**. It is the base rate for: * **STM-1** (Synchronous Transport Module level-1) * **OC-3** (Optical Carrier level-3) * Used extensively in routers, switches, and fiber-optic telecommunications equipment. #### C. Phase Jitter Components in this series are engineered for "Low Jitter" (often <1ps RMS). This ensures that when the signal travels through long-distance fiber or high-speed PCB traces, the timing remains accurate enough for the receiver to decode the data without errors. --- ### 4. Common Applications * Telecommunications (SONET/SDH/DWDM) * Data Communications (Gigabit Ethernet) * Storage Area Networks (Fiber Channel) * High-speed FPGA clocking