Datasheet




SDAS143C − APRIL 1982 − REVISED AUGUST 1995
Copyright  1995, Texas Instruments Incorporated
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251−1443
• 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
(C
L
= 50 pF)
(MHz)
TYPICAL POWER
DISSIPATION
PER FLIP-FLOP
(mW)
′ALS74A 50 6
′AS74A 134 26
description
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.
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 LXXLH
L LXXH
†
H
†
H H ↑ HHL
H H ↑ LLH
H H L X Q
0
Q
0
†
The output levels in this configuration are not
specified to meet the minimum levels for V
OH
if the
lows at PRE
and CLR are near V
IL
maximum.
Furthermore, this configuration is nonstable; that
is, it does not persist when PRE or CLR returns to
its inactive (high) level.
SN54ALS74A, SN54AS74A ...J PACKAGE
SN74ALS74A, SN74AS74A ...D OR N PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
14
13
12
11
10
9
8
1CLR
1D
1CLK
1PRE
1Q
1Q
GND
V
CC
2CLR
2D
2CLK
2PRE
2Q
2Q
SN54ALS74A, SN54AS74A . . . FK PACKAGE
(TOP VIEW)
3212019
910111213
4
5
6
7
8
18
17
16
15
14
2D
NC
2CLK
NC
2PRE
1CLK
NC
1PRE
NC
1Q
1D 1CLR NC
2Q 2Q
V 2CLR
1Q
NC
CC
NC − No internal connection
GND
  !" # $%&" !#  '%()$!" *!"&+
*%$"# $ " #'&$$!"# '& ",& "&#  &-!# #"%&"#
#"!*!* .!!"/+ *%$" '$&##0 *&# " &$&##!)/ $)%*&
"&#"0  !)) '!!&"&#+