HIT HD74AC298 Datasheet

HD74AC298/HD74ACT298

Quad 2-Input Multiplexer with Storage

Description

This device is a high-speed multiplexer with storage. 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 register is fully edge
triggered. The Data inputs (I0 and I1) and Select input (S) must be stable only one setup time prior to the
HIGH-to-LOW transition of the clock for predictable operation.

Features

• Outputs Source/Sink 24 mA

• HD74ACT298 has TTL-Compatible Inputs

Pin Arrangement

I

I1a

I0a

I0b

I1c

I1d

I0d

GND

1

1b

2

3

4

5

6

7

8

(Top view)

16

15

14

13

12

11

10

CC

V

Qa

Qb

Qc

Qd

CP

S

9

0c

I

HD74AC298/HD74ACT298

Logic Symbol

I0a I1a I0b I1b

S

CP

Qa Qb Qc Qd

Pin Names

I1a – I
I0a – I
S Select Input
CP Clock Pulse Input (Active Falling Edge)
Qa – QdOutputs

Source 1 Data Inputs

1d

Source 0 Data Inputs

0d

Function Table

Inputs Outputs
SCpQ

L a
H a
XH QA0Q

a

1

2

I0c I1c I0d I1d

Q

b

b

1

b

2

B0

Q

c

c

1

c

2

Q

C0

Q

d

d

1

d

2

Q

D0

2

Logic Diagram

S

CP

HD74AC298/HD74ACT298

I1a I0a I1b I0b I1c I0c I1d I0d

R

CP

SQa

R

CP

b

SQ

R

CP

c

SQ

R

CP

SQ

DC Characteristics (unless otherwise specified)

Item Symbol Max Unit Condition

Maximum quiescent supply current I

CC

80 µAV

= VCC or ground, VCC = 5.5 V,

IN

Ta = Worst case

Maximum quiescent supply current I

CC

8.0 µAV

= VCC or ground, VCC = 5.5 V,

IN

Ta = 25°C

Maximum ICC/input (HD74ACT298) I

CCT

1.5 mA VIN = VCC – 2.1 V, VCC = 5.5 V,
Ta = Worst case

AC Characteristics: HD74AC298

Ta = +25°C
C

= 50 pF

L

Item Symbol V

Maximum count f

max

(V)*1Min Typ Max Min Max Unit

CC

3.3 90 — — 70 — MHz
frequency 5.0 110 — — 100 —
Propagation delay t

PLH

3.3 1.0 7.0 10.0 1.0 11.5 ns
CP to Q 5.0 1.0 5.0 7.5 1.0 8.5
Propagation delay t

PHL

3.3 1.0 7.5 10.0 1.0 11.5
CP to Q 5.0 1.0 5.5 7.5 1.0 8.5

Note: 1. Voltage Range 3.3 is 3.3 V ± 0.3 V

Voltage Range 5.0 is 5.0 V ± 0.5 V

Ta = –40°C to +85°C
CL = 50 pF

d

QdQcQbQa

3