The part number **I641-31BB8O2-155.520** refers to a high-precision **Voltage Controlled Crystal Oscillator (VCXO)** typically manufactured by ILSI America (now part of Abracon). This component is designed for high-frequency telecommunications and networking applications. --- ### 1. Part Number Breakdown The alphanumeric string follows a specific coding structure to define the component's characteristics: | Code Segment | Description | Specific Detail | | :--- | :--- | :--- | | **I641** | Series Model | 5.0 x 7.0 mm Surface Mount VCXO | | **3** | Supply Voltage | 3.3V DC | | **1** | Stability | ±50 ppm (standard range) | | **BB** | Operating Temp | -40°C to +85°C (Industrial Grade) | | **8** | Pullability | ±80 ppm minimum | | **O2** | Output Type | CMOS Output | | **155.520** | Frequency | 155.520 MHz | --- ### 2. Technical Specifications This electronic part is a frequency control device used to generate a precise clock signal that can be slightly adjusted (pulled) by an external voltage. * **Package Size:** 7.0 x 5.0 x 1.8 mm (6-pad ceramic SMD). * **Frequency:** 155.520 MHz (Commonly used in SDH/SONET networking). * **Output Logic:** CMOS / HCMOS. * **Control Voltage:** Typically 1.65V center (range 0.3V to 3.0V). * **Phase Jitter:** Low jitter performance, optimized for high-speed data transmission. --- ### 3. Pin Configuration For the 6-pad I641 series, the standard pinout is usually: | Pin # | Function | Description | | :--- | :--- | :--- | | 1 | Vc | Voltage Control (Adjusts frequency) | | 2 | E/D or NC | Enable/Disable or No Connection | | 3 | GND | Case Ground | | 4 | Output | Clock Signal Output | | 5 | NC | No Connection | | 6 | Vdd | Supply Voltage (+3.3V) | --- ### 4. Typical Applications Due to the specific frequency of **155.520 MHz**, this part is primarily found in: * **Optical Networking:** SONET (OC-3) and SDH (STM-1) clock recovery. * **Phase-Locked Loops (PLL):** Used as the tunable element in timing circuits. * **Broadband Access:** Cable modems and base stations. * **Test & Measurement:** High-speed digital signal analysis.