DM54LS251

DM54LS251 DM74LS251 TRI-STATE Data Selectors Multiplexers June 1989 DM54LS251 DM74LS251 TRI-STATE Data Selectors Multiplexers General Description These data selectors multiplexers contain full on-chip binary decoding to select one-of-eight data sources and feature a strobe-controlled TRI-STATE output The strobe must be at a low logic level to enable these devices The TRI-STATE outputs permit direct connection to a common bus When the strobe input is high both outputs are in a high-impedance state in which both the upper and lower transistors of each totem-pole output are off and the output neither drives nor loads the bus significantly When the strobe is low the outputs are activated and operate as standard TTL totempole outputs To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels the output control circuitry is designed so that the average output disable time is shorter than the average output enable time Features Y Y Y Y Y Y Y Y TRI-STATE version of LS151 Interface directly with system bus Perform parallel-to-serial conversion Permit multiplexing from N-lines to one line Complementary outputs provide true and inverted data Maximum number of common outputs 54LS 49 74LS 129 Typical propagation delay time (D to Y) 54LS 17 ns 74LS 17 ns Typical power dissipation 54LS 35 mW 74LS 35 mW Connection Diagram Dual-In-Line Package Function Table Inputs Select C X L L L L H H H H B X L L H H L L H H A X L H L H L H L H Strobe S ...