SN54ALS74A, SN54AS74A, SN74ALS74A, SN74AS74A
DUAL POSITIVE-EDGE-TRIGGERED D-TYPE FLIP-FLOPS
WITH CLEAR AND PRESET
SDAS143C – APRIL 1982 – REVISED AUGUST 1995

•

SN54ALS74A, SN54AS74A . . . J PACKAGE
SN74ALS74A, SN74AS74A . . . D OR N PACKAGE
(TOP VIEW)

Package Options Include Plastic
Small-Outline (D) Packages, Ceramic Chip
Carriers (FK), and Standard Plastic (N) and
Ceramic (J) 300-mil DIPs

TYPE

TYPICAL MAXIMUM
CLOCK FREQUENCY
(CL = 50 pF)
(MHz)

1CLR
1D
1CLK
1PRE
1Q
1Q
GND

TYPICAL POWER
DISSIPATION
PER FLIP-FLOP
(mW)

′ALS74A

50

6

′AS74A

134

26

description

1

14

2

13

3

12

4

11

5

10

6

9

7

8

VCC
2CLR
2D
2CLK
2PRE
2Q
2Q

SN54ALS74A, SN54AS74A . . . FK PACKAGE
(TOP VIEW)

1D
1CLR
NC
VCC
2CLR

These devices contain two independent
positive-edge-triggered D-type flip-flops. A low
level at the preset (PRE) or clear (CLR) inputs sets
or resets the outputs regardless of the levels of the
other inputs. When PRE and CLR are inactive
(high), data at the data (D) input meeting the
setup-time requirements are transferred to the
outputs on the positive-going edge of the clock
(CLK) pulse. Clock triggering occurs at a voltage
level and is not directly related to the rise time of
CLK. Following the hold-time interval, data at the
D input can be changed without affecting the
levels at the outputs.

4

3 2 1 20 19
18

5

17

6

16

7

15

8

14
9 10 11 12 13

2D
NC
2CLK
NC
2PRE

1Q
GND
NC
2Q
2Q

1CLK
NC
1PRE
NC
1Q

NC – No internal connection

The SN54ALS74A and SN54AS74A are
characterized for operation over the full military
temperature range of – 55°C to 125°C. The
SN74ALS74A and SN74AS74A are characterized
for operation from 0°C to 70°C.
FUNCTION TABLE
INPUTS

OUTPUTS

PRE

CLR

CLK

D

Q

Q

L

H

X

X

H

L

H

L

X

X

H
H†

L

L

X

X

L
H†

H

H

↑

H

H

L

H

H

↑

L

L

H

H
H
L
X
Q0
Q0
† The output levels in this configuration are not
specified to meet the minimum levels for VOH if the
lows at PRE and CLR are near VIL maximum.
Furthermore, this configuration is nonstable; that
is, it does not persist when PRE or CLR returns to
its inactive (high) level.

Copyright  1995, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

1

SN54ALS74A, SN54AS74A, SN74ALS74A, SN74AS74A
DUAL POSITIVE-EDGE-TRIGGERED D-TYPE FLIP-FLOPS
WITH CLEAR AND PRESET
SDAS143C – APRIL 1982 – REVISED AUGUST 1995

logic symbol†
1PRE
1CLK
1D
1CLR
2PRE
2CLK
2D
2CLR

4

2
1

5

S

3

1Q

C1
1D

6

1Q

R

10

9

11

2Q

12
8
13

2Q

† This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for the D, J, and N packages.

logic diagram (positive logic)
PRE

CLR

Q

Q
CLK

D

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)‡
Supply voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Operating free-air temperature range, TA: SN54ALS74A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 55°C to 125°C
SN74ALS74A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
‡ Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

2

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

SN54ALS74A, SN54AS74A, SN74ALS74A, SN74AS74A
DUAL POSITIVE-EDGE-TRIGGERED D-TYPE FLIP-FLOPS
WITH CLEAR AND PRESET
SDAS143C – APRIL 1982 – REVISED AUGUST 1995

recommended operating conditions
SN54ALS74A

SN74ALS74A

MIN

NOM

MAX

MIN

NOM

MAX

4.5

5

5.5

4.5

5

5.5

UNIT

VCC
VIH

Supply voltage

VIL
IOH

Low-level input voltage

0.7

0.8

High-level output current

– 0.4

– 0.4

mA

IOL
fclock

Low-level output current

4

8

mA

34

MHz

High-level input voltage

2

Clock frequency

0
PRE or CLR low

tw

2

Pulse duration

tsu

Set p time before CLK↑
Setup

th
TA

Hold time after CLK↑

25

15

CLK high

17.5

14.5

CLK low

17.5

14.5

Data

16

15

PRE or CLR inactive

10

10

Data

Operating free-air temperature

2

V

0

15

125

V

ns

ns

0

– 55

V

ns

0

70

°C

electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER

TEST CONDITIONS

VIK
VOH

VCC = 4.5 V,
VCC = 4.5 V to 5.5 V,

II = –18 mA
IOH = – 2 mA

VOL

VCC = 4
4.5
5V

IOL = 4 mA
IOL = 8 mA

VCC = 4
4.5
5V
V,

VI = 7 V

VCC = 4
4.5
5V
V,

VI = 2
2.7
7V

VCC = 4
4.5
5V
V,

VI = 0
0.4
4V

II
IIH
IIL

CLK or D
PRE or CLR
CLK or D
PRE or CLR
CLK or D
PRE or CLR

SN54ALS74A
MIN TYP†
MAX

SN74ALS74A
MIN TYP†
MAX

–1.5
VCC – 2

–1.5
VCC – 2

0.25

0.4

UNIT
V
V

0.25

0.4

0.35

0.5

0.1

0.1

0.2

0.2

20

20

40

40

– 0.2

– 0.2

– 0.4

– 0.4

V
mA
µA
mA

IO‡
VCC = 5.5 V,
VO = 2.25 V
– 20
–112
– 30
–112
mA
ICC
VCC = 5.5 V,
See Note 1
2.4
4
2.4
4
mA
† All typical values are at VCC = 5 V, TA = 25°C.
‡ The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS.
NOTE 1: ICC is measured with D, CLK, and PRE grounded, then with D, CLK, and CLR grounded.

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

3

SN54ALS74A, SN54AS74A, SN74ALS74A, SN74AS74A
DUAL POSITIVE-EDGE-TRIGGERED D-TYPE FLIP-FLOPS
WITH CLEAR AND PRESET
SDAS143C – APRIL 1982 – REVISED AUGUST 1995

switching characteristics (see Figure 1)

FROM
(INPUT)

PARAMETER

VCC = 4.5 V to 5.5 V,
CL = 50 pF,
RL = 500 Ω,
TA = MIN to MAX†
SN54ALS74A SN74ALS74A

TO
(OUTPUT)

MIN
fmax
tPLH
tPHL
tPLH

MAX

MIN

25
PRE or CLR

Q or Q

MAX

34

MHz

3

18

3

13

5

17

5

15

5

16

5

18

5
23
CLK
Q or Q
tPHL
5
20
† For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.

UNIT

ns
ns

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)‡
Supply voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Operating free-air temperature range, TA: SN54AS74A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 55°C to 125°C
SN74AS74A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
‡ Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

recommended operating conditions
SN54AS74A

SN74AS74A

MIN

NOM

MAX

MIN

NOM

MAX

4.5

5

5.5

4.5

5

5.5

UNIT

VCC
VIH

Supply voltage

VIL
IOH

Low-level input voltage

0.8

0.8

V

High-level output current

–2

–2

mA

IOL
fclock*

Low-level output current

20

20

mA

105

MHz

tw*

Pulse duration

High-level input voltage

2

Clock frequency

tsu*

Set p time before CLK↑
Setup

th*
TA

Hold time after CLK↑

0

2

90

0

PRE or CLR low

4

CLK high

4

4

CLK low

5.5

5.5

Data

4.5

4.5

2

2

PRE or CLR inactive
Data

Operating free-air temperature

V

4

0
– 55

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

ns

ns

0
125

0

* On products compliant to MIL-STD-833, Class B, this parameter is based on characterization data but is not production tested.

4

V

ns
70

°C

SN54ALS74A, SN54AS74A, SN74ALS74A, SN74AS74A
DUAL POSITIVE-EDGE-TRIGGERED D-TYPE FLIP-FLOPS
WITH CLEAR AND PRESET
SDAS143C – APRIL 1982 – REVISED AUGUST 1995

electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER

TEST CONDITIONS

VIK
VOH

VCC = 4.5 V,
VCC = 4.5 V to 5.5 V,

II = –18 mA
IOH = – 2 mA

VOL
II

VCC = 4.5 V,
VCC = 5.5 V,

IOL = 20 mA
VI = 7 V

IIH
IIL

CLK or D
PRE or CLR
CLK or D
PRE or CLR

VCC = 5
5.5
5V
V,

VI = 2
2.7
7V

VCC = 5
5.5
5V
V,

VI = 0
0.4
4V

SN54AS74A
TYP†
MAX

MIN

SN74AS74A
TYP†
MAX

MIN

–1.2
VCC – 2

–1.2
VCC – 2

0.25

0.5

UNIT
V
V

0.25

0.5

V

0.1

0.1

mA

20

20

40

40

– 0.5

– 0.5

–1.8

–1.8

µA
mA

IO‡
VCC = 5.5 V,
VO = 2.25 V
– 30
–112
– 30
–112
mA
ICC
VCC = 5.5 V,
See Note 1
10.5
16
10.5
16
mA
† All typical values are at VCC = 5 V, TA = 25°C.
‡ The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS.
NOTE 1: ICC is measured with D, CLK, and PRE grounded, then with D, CLK, and CLR grounded.

switching characteristics (see Figure 1)

PARAMETER

FROM
(INPUT)

TO
(OUTPUT)

VCC = 4.5 V to 5.5 V,
CL = 50 pF,
RL = 500 Ω,
TA = MIN to MAX§
SN54AS74A
MIN

fmax*
tPLH
tPHL
tPLH

MAX

90
PRE or CLR

Q or Q

CLK

Q or Q

UNIT

SN74AS74A
MIN

MAX

105

MHz

2

9

2

7.5

2.5

11.5

2.5

10.5

2.5

10

3

8

tPHL
3.5
10.5
3
9
* On products compliant to MIL-STD-833, Class B, this parameter is based on characterization data but is not production tested.
§ For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

ns
ns

5

SN54ALS74A, SN54AS74A, SN74ALS74A, SN74AS74A
DUAL POSITIVE-EDGE-TRIGGERED D-TYPE FLIP-FLOPS
WITH CLEAR AND PRESET
SDAS143C – APRIL 1982 – REVISED AUGUST 1995

PARAMETER MEASUREMENT INFORMATION
SERIES 54ALS/74ALS AND 54AS/74AS DEVICES
7V
RL = R1 = R2

VCC
S1
RL
R1

Test
Point

From Output
Under Test
CL
(see Note A)

From Output
Under Test

RL

Test
Point

From Output
Under Test
CL
(see Note A)

CL
(see Note A)

LOAD CIRCUIT FOR
BI-STATE
TOTEM-POLE OUTPUTS

LOAD CIRCUIT
FOR OPEN-COLLECTOR OUTPUTS

3.5 V

Timing
Input

Test
Point

LOAD CIRCUIT
FOR 3-STATE OUTPUTS

3.5 V

High-Level
Pulse

1.3 V

R2

1.3 V

1.3 V
0.3 V

0.3 V

Data
Input

tw

th

tsu

3.5 V
1.3 V

3.5 V

Low-Level
Pulse

1.3 V
0.3 V

1.3 V

0.3 V

VOLTAGE WAVEFORMS
SETUP AND HOLD TIMES

VOLTAGE WAVEFORMS
PULSE DURATIONS

3.5 V

Output
Control
(low-level
enabling)

1.3 V

1.3 V
0.3 V

tPZL
Waveform 1
S1 Closed
(see Note B)

tPLZ

[3.5 V

1.3 V

tPHZ
tPZH
Waveform 2
S1 Open
(see Note B)

1.3 V

VOL
0.3 V
VOH

1.3 V

0.3 V

[0 V

3.5 V
1.3 V

Input

1.3 V
0.3 V
tPHL

tPLH

VOH

In-Phase
Output

1.3 V

1.3 V
VOL
tPLH

tPHL

VOH

Out-of-Phase
Output
(see Note C)

1.3 V

1.3 V
VOL

VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES

VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES, 3-STATE OUTPUTS

NOTES: A. CL includes probe and jig capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.
C. When measuring propagation delay items of 3-state outputs, switch S1 is open.
D. All input pulses have the following characteristics: PRR ≤ 1 MHz, tr = tf = 2 ns, duty cycle = 50%.
E. The outputs are measured one at a time with one transition per measurement.

Figure 1. Load Circuits and Voltage Waveforms

6

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Copyright  1998, Texas Instruments Incorporated