The B9949 is a low-voltage clock distribution buffer with the capability to select either a differential LVPECL or LVCMOS/LVTTL compatible input clocks. These clock sources can be used to provide for test clocks as well as the primary system clocks. All other control inputs are LVCMOS/LVTTL compatible. The 15 outputs are 3.3V LVCMOS or LVTTL compatible and can drive two series terminated 50 transmission lines. With this capability the B9949 has an effective fan-out of 1:30.