器件名称:
74HC257
功能描述:
High Speed CMOS Logic Quad 2-Input Multiplexer with Three-State Non-Inverting Outputs
文件大小:
52.16KB 共7页
简 介:
Data sheet acquired from Harris Semiconductor SCHS171 CD74HC257, CD74HCT257 High Speed CMOS Logic Quad 2-Input Multiplexer with Three-State Non-Inverting Outputs Description The Harris CD74HC257 and CD74HCT257 are quad 2-input multiplexers which select four bits of data from two sources under the control of a common Select Input (S). The Output Enable input (OE) is active LOW. When OE is HIGH, all of the outputs (1Y-4Y) are in the high impedance state regardless of all other input conditions. Moving data from two groups of registers to four common output busses is a common use of the 257. The state of the Select input determines the particular register from which the data comes. It can also be used as a function generator. November 1997 Features Buffered Inputs Typical Propagation Delay ( In to Output ) = 12ns at VCC = 5V, CL = 15pF, TA = 25oC Fanout (Over Temperature Range) - Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads - Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads Wide Operating Temperature Range . . . -55oC to 125oC Balanced Propagation Delay and Transition Times Signicant Power Reduction Compared to LSTTL Logic ICs HC Types - 2V to 6V Operation - High Noise Immunity: NIL = 30%, NIH = 30% of VCC at VCC = 5V HCT Types - 4.5V to 5.5V Operation - Direct LSTTL Input Logic Compatibility, VIL= 0.8V (Max), VIH = 2V (Min) - CMOS Input Compatibility, Il ≤ 1A at VOL, VOH [ /Title (CD74 HC257 , CD74 HCT25 7) /Subject (High Speed CMOS Logic……
