54LS257

54LS257 Description

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54LS257 Manufacturer

54LS257 Datasheet (PDF)

54LS257 Price & Availability

54LS257 Features

• TRI-STATE versions LS157 and LS158 with same pin-outs
• Schottky-clamped for significant improvement in A-C performance
• Provides bus interface from multiple sources in high-performance systems
• Average propagation delay from data input 12 ns
• Typical power dissipation LS257B 50 mW LS258B 35 mW
• Alternate military/aerospace devices (54LS257A/54LS258A) are available. Contact a National Semiconductor Sales Office/Distributor for specifications.

54LS257 Description

These Schottky-clamped high-performance multiplexers feature TRI-STATE outputs that can interface directly with data lines of bus-organized systems. With all but one of the common outputs disabled (at a high impedance state), the low impedance of the single enabled output will drive the bus line to a high or low logic level. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output enable circuitry is designed such that the output disable times are shorter than the output enable times.

This TRI-STATE output feature means that n-bit (paralleled) data selectors with up to 258 sources can be implemented for data buses. It also permits the use of standard TTL registers for data retention throughout the system.

54LS257 Parameters

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