The CY29940 is a low-voltage 200-MHz clock distribution buffer with the capability to select either a differential LVPECL or a LVCMOS/LVTTL compatible input clock. The two clock sources can be used to provide for a test clock as well as the primary system clock. All other control inputs are LVCMOS/LVTTL compatible. The eighteen outputs are 2.5V or 3.3V LVCMOS/LVTTL compatible and can drive 50 series or parallel terminated transmission lines. For series terminated transmission lines, each output can drive one or two traces giving the device an effective fanout of 1:36. Low output-to-output skews make the CY29940 an ideal clock distribution buffer for nested clock trees in the most demanding of synchronous systems.