74LS257中文资料仙童半导体数据手册PDF规格书

General Description

These Schottky-clamped high-performance multiplexers feature 3-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.

特性 Features

■ 3-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: 50 mW