The 557-01 is a clock chip designed for use in PCI Express® cards as a clock source. It provides a pair of differential outputs at 100MHz in a small 8-pin SOIC package. Using Renesas' patented Phase-Locked Loop (PLL) techniques, the device takes a 25MHz crystal input and produces HCSL (Host Clock Signal Level) differential outputs at 100MHz clock frequency. LVDS signal levels can also be supported via an alternative termination scheme.