5-474

FAST AND LS TTL DATA

SN54/74LS298

LOGIC OR BLOCK DIAGRAM

S

I1a

I0a

I1b

I0b

I1c

I0c

I1d

I0d

CP

R

CP

S Qa

R

CP

S Qb

Qa

Qb

Qc

Qd

14

1

2

6

7

3

4

5

9

11

12

10

13

15

VCC = PIN 16

GND = PIN 8

= PIN NUMBERS

R

CP

S Qc

R

CP

S Qd

FUNCTIONAL DESCRIPTION

The LS298 is a high speed Quad 2-Port Register. It selects

four bits of data from two sources (ports)under the control of a

Common Select Input (S). The selected data is transferred to

the 4-bit output register synchronous with the HIGH to LOW

transition of the Clock input (CP). The 4-bit output register is

fully edge-triggered. The Data inputs (I) and Select input (S)

must be stable only one setup time prior to the HIGH to LOW

transition of the clock for predictable operation.

TRUTH TABLE

INPUTS

OUTPUT

S

I0

I1

Q

I

I

X

L

I

h

X

H

h

X

I

L

h

X

h

H

L = LOW Voltage Level

H = HIGH Voltage Level

X = Don’t Care

I = LOW Voltage Level one setup time prior to the HIGH to LOW clock transition.

h = HIGH Voltage Level one setup time prior to the HIGH to LOW clock transition.

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

VCC

Supply Voltage

54

74

4.5

4.75

5.0

5.0

5.5

5.25

V

TA

Operating Ambient Temperature Range

54

74

– 55

0

25

25

125

70

°C

IOH

Output Current — High

54, 74

– 0.4

mA

IOL

Output Current — Low

54

74

4.0

8.0

mA