DSC557 2-Output MEMS Clock Generator Microchip Technology DSC557 2-Output MEMS Clock Generator is a crystal-less, two output PCI express clock generator meeting Gen1, Gen2, Gen3, and Gen4 specifications. By eliminating the external quartz crystal, the DSC557 significantly enhances reliability and accelerates product development. This DSC557-03 clock generator has an output enable/disable a feature that allows disabling the outputs when OE is low. The device is available in two different packages a space-saving 14-pin QFN (77% less board space) and a 16-pin TSSOP that is a “drop-in” replacement to the existing ICS557-03 clock.