TI SN74LS251N

These monolithic data selectors/multiplexers contain full on-chip binary decoding to select one-of-eight data sources and feature a strobe-controlled threestate output. The strobe must be at a low logic level to enable these devices. The three-state outputs permit a number of outputs to be connected 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 activatedandoperateasstandardTTLtotem-pole 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 averageoutputenabletime.TheSN54251and SN74251have output clampdiodes toattenuate reflectionsonthebusline.

• Three-state outputs for direct system bus interfacing
• Parallel-to-serial conversion support
• N-to-1 multiplexing capability
• Complementary outputs for simultaneous true and inverted data
• Full compatibility with most TTL circuits
• On-chip full binary decoding for 8-to-1 data selection
• Strobe control for output enable/disable
• Optimized output control circuitry to reduce bus contention
• Output clamping diodes on select models to attenuate bus signal reflections
• Multiple package options available
• Maximum supply voltage: 7V
• Operating temperature range: -55℃ to 125℃ or 0℃ to 70℃ depending on model
• Storage temperature range: -65℃ to 150℃

• System bus multiplexing
• Parallel-to-serial data conversion
• Multi-source data selection