DM74S251 Datasheet | National Semiconductor

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 mon 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 mon 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 TRI-STATE version of S151 Interface directly with system bus Perform parallel-to-serial conversion Permit multiplexing from N-lines to one line plementary outputs provide true and inverted data Max no of mon outputs 54S 39 74S 129 Typical propagation delay time (D to Y) 8 ns Typical power dissipation 275 m W Connection Diagram 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 H L L L L L L L L Outputs Y Z D0 D1 D2 D3 D4 D5 D6 D7 W Z D0 D1 D2 D3 D4 D5 D6 D7 H e High Logic Level L e Low Logic Level X e Don’t Care Z e High Impedance (Off) D0 D1 TL F 6480 - 1 D7 e The Level of the respective D input Order Number DM54S251J or DM74S251N See NS Package Number J16A or N16E TRI-STATE is a registered trademark of National Semiconductor Corporation C1995 National Semiconductor Corporation TL F 6480 RRD-B30M105 Printed in U S A Absolute Maximum Ratings (Note) If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage 7V Input Voltage 5 5V Operating Free Air Temperature...