器件名称: 74HC257
功能描述: Quad 2-Input Data Selector/Multiplexer with 3-State Outputs
文件大小: 175.28KB 共6页
简 介:MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
Quad 2-Input Data Selector/Multiplexer with 3-State Outputs
High–Performance Silicon–Gate CMOS
The MC74HC257 is identical in pinout to the LS257. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LSTTL outputs. This device selects a (4–bit) nibble from either the A or B inputs as determined by the Select input. The nibble is presented at the outputs in noninverted form when the Output Enable pin is at a low level. A high level on the Output Enable pin switches the outputs into the high–impedance state. The HC257 is similar in function to the HC157 which do not have 3–state outputs. Output Drive Capability: 15 LSTTL Loads Outputs Directly Interface to CMOS, NMOS, and TTL Operating Voltage Range: 2 to 6 V Low Input Current: 1 A High Noise Immunity Characteristic of CMOS Devices In Compliance with the Requirements Defined by JEDEC Standard No. 7A Chip Complexity: 108 FETs or 27 Equivalent Gates
16
MC74HC257
N SUFFIX PLASTIC PACKAGE CASE 648–08
1
16 1
D SUFFIX SOIC PACKAGE CASE 751B–05
ORDERING INFORMATION MC74HCXXXN MC74HCXXXD Plastic SOIC
PIN ASSIGNMENT
SELECT A0 B0 Y0 A1 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCC OUTPUT ENABLE A3 B3 Y3 A2 B2 Y2
LOGIC DIAGRAM
2 5 11 14 4 3 6 10 13 7 9 12 Y0 Y1 Y2 Y3 NONINVERTING NIBBLE OUTPUT
B1 Y1 GND
A0 NIBBLE A INPUT A1 A2 A3 B0 NIBBLE B INPUT B1 B2 B3
FUNCTION TABLE
Inputs Output Enable H L L Select X L H Outputs Y0 – Y3 Z A0 –……
