## Overview of the VCC6-R Series The **VCC6-R** is a high-performance, low-jitter **Voltage Controlled Crystal Oscillator (VCXO)** manufactured by **Vectron International** (now part of Microchip Technology). It is specifically designed for high-speed data communications and precision timing applications. --- ### 1. Key Technical Specifications | Parameter | Specification Details | | :--- | :--- | | **Output Type** | LVPECL (Low-Voltage Positive Emitter-Coupled Logic) | | **Frequency Range** | 10 MHz to 270 MHz (Standard) | | **Supply Voltage (Vcc)** | +3.3 Vdc (±5%) | | **Operating Temperature** | -10°C to +70°C (Standard) / -40°C to +85°C (Industrial) | | **Package Size** | 5.0 x 7.0 x 1.8 mm (Standard 6-pad SMD) | | **Jitter** | < 1 ps RMS (12 kHz to 20 MHz) | | **Control Voltage** | 0.3V to 3.0V (Standard for 3.3V supply) | --- ### 2. Pin Configuration (6-Pad Layout) The VCC6-R uses a standard industry footprint for high-speed oscillators. | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | **VC** | Control Voltage (Input to adjust frequency) | | **2** | **E/D or NC** | Enable/Disable (Logic 1 = Output, Logic 0 = High Z) | | **3** | **GND** | Case and Circuit Ground | | **4** | **Output** | LVPECL Output | | **5** | **Complementary Output** | Complementary LVPECL Output | | **6** | **Vcc** | Supply Voltage (+3.3V) | --- ### 3. Core Electronic Features #### A. LVPECL Output Logic The "R" in VCC6-R typically signifies the **LVPECL** output configuration. LVPECL is preferred in high-frequency designs because: * It offers high-speed switching capabilities. * It provides excellent noise immunity due to differential signaling. * It maintains a constant current draw, reducing power supply noise. #### B. Voltage Control (VCXO) Functionality Unlike a standard fixed-frequency oscillator, the VCC6-R allows the output frequency to be "pulled" or tuned slightly by applying a DC voltage to Pin 1. This is critical for: * **Phase-Locked Loops (PLLs):** Synchronizing the oscillator to an external reference clock. * **Frequency Modulation:** Fine-tuning the clock to compensate for aging or temperature drift. #### C. Low Phase Jitter The internal circuitry is optimized to minimize "phase noise." In high-speed networking (like 10G Ethernet or Fibre Channel), low jitter is essential to prevent data bit errors. --- ### 4. Typical Applications * **Networking:** SONET / SDH, Gigabit Ethernet, and 10GbE. * **Storage:** Fibre Channel and SAN infrastructure. * **Broadcasting:** Digital video synchronization. * **FPGA Clocking:** Providing high-speed differential clocks to Xilinx or Altera FPGAs. --- ### 5. Implementation Example (Termination) Since the VCC6-R uses LVPECL, the output requires specific termination to GND (typically 50 ohms to $V_{cc}-2.0V$) to maintain signal integrity. ```c // Simplified LVPECL Termination Logic VCC (3.3V) --- [Resistor 1] --- Output Pin | --- [Resistor 2] --- GND // Note: Actual termination often uses a Thevenin equivalent // or 50 ohms to a biased termination voltage (Vtt). ```