54LS257A/DM54LS257B/DM74LS257B, 54LS258A/DM54LS258B/DM74LS258B TRI-STATE® Quad 2-Data Selectors/Multiplexers
■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.
●Features
■TRI-STATE versions LS157 and LS158 with same pinouts
■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.
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54LS257A 、 DM54LS257B 、 DM74LS257B 、 54LS258A 、 DM54LS258B 、 DM74LS258B 、 LS157 、 LS257B 、 LS258B 、 LS158 、 54LS257ADMQB 、 54LS257ALMQB 、 DM54LS257BJ 、 DM54LS257BW 、 DM74LS257BM 、 DM74LS257BN 、 54LS258ADMQB 、 54LS258AFMQB 、 54LS258ALMQB 、 DM54LS258BJ 、 DM54LS258BW 、 DM74LS258BM 、 DM74LS258BN 、 54LS 、 DM54LS 、 DM74LS 、 DM54 、 DM74 、 54LS257AFMQB |
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Quad 2-Data Selectors/Multiplexers 、 Schottky-clamped high-performance multiplexers |
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Datasheet |
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Please see the document for details |
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DIP |
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English Chinese Chinese and English Japanese |
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June 1989 |
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TL /F/6417 |
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407 KB |
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