HIT HD74HC42 Datasheet

HD74HC42

BCD-to-Decimal Decoder

Description

Data on the four input pins select one of the 10 outputs corresponding to the value of the BCD number on
the inputs. An output will go low when selected, otherwise it remains high. If the input data is not a valid
BCD number all outputs will remain high.

Features

• High Speed Operation: tpd = 13 ns typ (CL = 50 pF)

• High Output Current: Fanout of 10 LSTTL Loads

• Wide Operating Voltage: VCC = 2 to 6 V

• Low Input Current: 1 µA max

• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)

HD74HC42

Function Table

BCD Inputs Decimal Outputs

No. DCBA0123456789

0 LLLLLHHHHHHHHH
1 LLLHHLHHHHHHHH
2 LLHLHHLHHHHHHH
3 LLHHHHHLHHHHHH
4 LHLLHHHHLHHHHH
5 LHLHHHHHHLHHHH
6 LHHLHHHHHHLHHH
7 LHHHHHHHHHHLHH
8 HLLLHHHHHHHHLH
9 HLLHHHHHHHHHHL
INVALID H L H L HHHHHHHHHH

HLHHHHHHHHHHHH
HHLLHHHHHHHHHH
HHLHHHHHHHHHHH
HHHLHHHHHHHHHH
HHHHHHHHHHHHHH

Pin Arrangement

0Y

1Y

2Y

3Y

Outputs

4Y

5Y

6Y

GND

V

1

0

2

3

4

5

6

7

8

A

1
2
3

B
4
5

C
6

7
8

D
9

(Top view)

16

15

14

13

12

11

10

CC

A

B

C

D

9Y

8Y

Outputs Inputs

9

7Y

2

Logic Diagram

HD74HC42

0Y
1Y

A

B

C

D

2Y
3Y
4Y
5Y
6Y
7Y
8Y
9Y

3