CD54HC257F3A

CD54HC257F3A Features

• Buffered Inputs • Typical Propagation Delay ( In to Output ) = 12ns atVCC = 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 • Significant Power Reduction Compared to LSTTLLogic ICs • HC Types- 2V to 6V Operation- High Noise Immunity: NIL = 30%, NIH = 30% of VCCat 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 ≤ 1µA at VOL, VOH

CD54HC257F3A Description

The ’HC257 and ’HCT257 are quad 2-input multiplexerswhich select four bits of data from two sources under thecontrol of a common Select Input (S). The Output Enableinput (OE) is active LOW. When OE is HIGH, all of the out-puts (1Y-4Y) are in the high impedance state regardless ofall other input conditions.Moving data from two groups of registers to four commonoutput buses is a common use of the 257. The state of theSelect input determines the particular register from whichthe data comes. It can also be used as a function generator.