The B9947 is a low-voltage clock distribution buffer with the capability to select one of two LVCMOS/LVTTL compatible clock inputs. 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 nine outputs are 3.3V LVCMOS or LVTTL compatible and can drive two series terminated 50 transmission lines. With this capability the B9947 has an effective fanout of 1:18. The outputs can also be three-stated via the three-state input TS#. Low output-to-output skews make the B9947 an ideal clock distribution buffer for nested clock trees in the most demanding of synchronous systems.