Si522xx PCIe Clock Generators Skyworks Si522xx PCIe Clock Generators Gen 1/2/3/4 designed for highest performance and lowest power PCI-Express clock generators for 1.5V to 1.8V power supply. These clock generators feature individual hardware control pins for enabling and disabling each output and spread spectrum for EMI reduction. The clock generators offer 133MHz or 200MHz differential output frequencies which can also be controlled via I2C.