### Overview of PL602-21SC-R The **PL602-21SC-R** (often abbreviated within the PL602 family) is a high-performance, low-power **HCSL (Host Clock Signal Level)** clock generator. It is specifically designed for PCI Express (PCIe) applications, providing a high-speed differential output from a standard crystal input. --- ### Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Part Number** | PL602-21SC-R | | **Manufacturer** | Microchip Technology (formerly PhaseLink/Micrel) | | **Output Type** | HCSL (Differential) | | **Input Frequency** | 25MHz Crystal | | **Output Frequency** | 100MHz (typically) | | **Supply Voltage (VDD)** | 2.5V to 3.3V | | **Operating Temperature** | 0°C to +70°C (Commercial) | | **Package Type** | SOP-8 (Standard Outline Package) | --- ### Core Electronic Functions #### 1. Phase-Locked Loop (PLL) The core of the device is an integrated PLL that multiplies the reference frequency. In most PCIe applications, it takes a **25MHz** crystal input and synthesizes a high-precision **100MHz** output clock with extremely low phase jitter. #### 2. HCSL Driver The output buffer is specifically designed for HCSL signaling. This is the standard for PCI Express because it allows for fast switching speeds and high signal integrity over PCB traces without requiring significant power. #### 3. Low Jitter Performance Jitter refers to the timing deviations in the clock signal. The PL602 series is engineered to meet the strict jitter requirements of: * PCIe Gen 1 * PCIe Gen 2 * PCIe Gen 3 --- ### Pin Configuration (SOP-8) | Pin # | Name | Description | | :--- | :--- | :--- | | 1 | XIN | Crystal Input | | 2 | XOUT | Crystal Output | | 3 | VDD | Power Supply | | 4 | FSEL | Frequency Select (Internal pull-up) | | 5 | CLK_N | Negative Differential Output | | 6 | CLK_P | Positive Differential Output | | 7 | GND | Ground | | 8 | OE | Output Enable (Active High) | --- ### Typical Application Circuit When integrating this part into a circuit, the following external components are usually required: ```c // Layout Recommendations - Place 0.1uF and 0.01uF decoupling capacitors near VDD (Pin 3). - Ensure 33-50 Ohm series termination resistors are used on CLK_P/CLK_N. - Keep differential traces equal in length to prevent skew. ``` ---