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ꢉ ꢊꢄꢅꢈꢋ ꢌ ꢀꢍꢎ ꢍꢏ ꢐꢑꢐꢉ ꢒꢐ ꢑꢎ ꢓꢍꢒ ꢒ ꢐꢓꢐ ꢉꢈꢉ ꢑꢎ ꢔꢋꢐ ꢈꢕ ꢅꢍ ꢋ ꢑ ꢕꢅꢌ ꢋ ꢀ
ꢖ ꢍꢎ ꢗꢈ ꢘꢅꢐ ꢄꢓꢈꢄꢁꢉꢈ ꢋ ꢓꢐ ꢀ ꢐꢎ
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
1CLR
1D
1CLK
1PRE
1Q
V
CC
2CLR
1
2
3
4
5
6
7
14
13
12
11
10
9
TYPICAL MAXIMUM
CLOCK FREQUENCY
TYPICAL POWER
2D
DISSIPATION
PER FLIP-FLOP
(mW)
TYPE
2CLK
2PRE
2Q
(C = 50 pF)
L
(MHz)
50
1Q
GND
′ALS74A
′AS74A
6
2Q
8
134
26
description
SN54ALS74A, SN54AS74A . . . FK PACKAGE
(TOP VIEW)
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.
3
2
1
20 19
18
1CLK
NC
2D
17 NC
4
5
6
7
8
16
15
14
1PRE
NC
2CLK
NC
1Q
2PRE
9 10 11 12 13
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
L
CLR
CLK
X
D
X
X
X
H
L
Q
H
L
Q
L
H
L
H
X
H
†
†
H
L
L
X
H
H
H
H
H
↑
H
L
L
H
↑
H
H
L
X
Q
Q
0
0
†
The output levels in this configuration are not
specified to meet the minimum levels for V if the
OH
lows at PRE and CLR are near V maximum.
IL
Furthermore, this configuration is nonstable; that
is, it does not persist when PRE or CLR returns to
its inactive (high) level.
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Copyright 1995, Texas Instruments Incorporated
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1
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