DM74LS373/DM74LS374 3-STATE Octal D-Type Transparent Latches and Edge-Triggered
Flip-Flops
March 1998
DM74LS373/DM74LS374
3-STATE Octal D-Type Transparent Latches and
Edge-Triggered Flip-Flops
General Description
These 8-bit registers feature totem-pole 3-STATE outputs
designed specifically for driving highly-capacitive or rela-
tively low-impedance loads. The high-impedance state and
increased high-logic level drive provide these registers with
the capability of being connected directly to and driving the
bus lines in a bus-organized system without need for inter-
face or pull-up components. They are particularly attractive
for implementing buffer registers, I/O ports, bidirectional bus
drivers, and working registers.
The eight latches of the DM54/74LS373 are transparent
D-type latches meaning that while the enable (G) is high the
Q outputs will follow the data (D) inputs. When the enable is
taken low the output will be latched at the level of the data
that was set up.
The eight flip-flops of the DM54/74LS374 are edge-triggered
D-type flip flops. On the positive transition of the clock, the Q
outputs will be set to the logic states that were set up at the
D inputs.
A buffered output control input can be used to place the eight
outputs in either a normal logic state (high or low logic levels)
or a high-impedance state. In the high-impedance state the
outputs neither load nor drive the bus lines significantly.
The output control does not affect the internal operation of
the latches or flip-flops. That is, the old data can be retained
or new data can be entered even while the outputs are off.
Features
n
Choice of 8 latches or 8 D-type flip-flops in a single
package
n
3-STATE bus-driving outputs
n
Full parallel-access for loading
n
Buffered control inputs
n
P-N-P inputs reduce D-C loading on data lines
Connection Diagrams
Dual-In-Line Packages
’LS373
DS006431-1
Order Number DM54LS373J, DM54LS373W, DM74LS373N or DM74LS373WM
See Package Number J20A, M20B, N20A or W20A
© 1998 Fairchild Semiconductor Corporation
DS006431
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Connection Diagrams
(Continued)
’LS374
DS006431-2
Order Number DM54LS374J, DM54LS374W, DM74LS374WM or DM74LS374N
See Package Number J20A, M20B, N20A or W20A
Function Tables
DM54/74LS373
Output
Control
L
L
L
H
Enable
G
H
H
L
X
H
L
X
X
H
L
Q
0
Z
D
Output
H = High Level (Steady State), L = Low Level (Steady State), X = Don’t Care
↑
= Transition from low-to-high level, Z = High Impedance State
Q
0
= The level of the output before steady-state input conditions were estab-
lished.
DM54/74LS374
Output
Control
L
L
L
H
↑
↑
Clock
D
H
L
X
X
Output
H
L
Q
0
Z
L
X
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2
Absolute Maximum Ratings
(Note 1)
Supply Voltage
Input Voltage
Storage Temperature Range
7V
7V
−65˚C to +150˚C
Operating Free Air Temperature Range
DM54LS
DM74LS
−55˚C to +125˚C
0˚C to +70˚C
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
t
W
t
SU
t
H
T
A
Parameter
Min
Supply Voltage
High Level Input Votage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Pulse Width
(Note 3)
Enable High
Enable Low
15
15
5
↓
20
↓
−55
125
4.5
2
0.7
−1
12
15
15
5
↓
20
↓
0
70
ns
ns
˚C
DM54LS373
Nom
5
Max
5.5
Min
4.75
2
0.8
−2.6
24
DM74LS373
Nom
5
Max
5.25
V
V
V
mA
mA
ns
Units
Data Setup Time (Notes 2, 3)
Data Hold Time (Notes 2, 3)
Free Air Operating Temperature
Note 1:
The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these
limits. The parametric values defined in the “Electrical Characteristics” table are not guaranteed at the absolute maximum ratings. The “Recommended Operating
Conditions” table will define the conditions for actual device operation.
Note 2:
The symbol (
↓
) indicates the falling edge of the clock pulse is used for reference.
Note 3:
T
A
= 25˚C and V
CC
= 5V.
’LS373 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
V
OH
Parameter
Input Clamp Voltage
High Level Output Voltage
Conditions
V
CC
= Min, I
I
= −18 mA
V
CC
= Min
I
OH
= Max
V
IL
= Max
V
IH
= Min
V
OL
Low Level Output Voltage
V
CC
= Min
I
OL
= Max
V
IL
= Max
V
IH
= Min
I
OL
= 12 mA
V
CC
= Min
I
I
I
IH
I
IL
I
OZH
Input Current
@
Max
Input Voltage
High Level Input Current
Low Level Input Current
Off-State Output Current
with High Level Output
Voltage Applied
I
OZL
Off-State Output Current
with Low Level Output
Voltage Applied
I
OS
Short Circuit
Output Current
V
CC
= Max
(Note 5)
DM54
DM74
−20
−50
−100
−225
mA
V
CC
= Max, V
O
= 0.4V
V
IH
= Min, V
IL
= Max
−20
µA
V
CC
= Max, V
I
= 2.7V
V
CC
= Max, V
I
= 0.4V
V
CC
= Max, V
O
= 2.7V
V
IH
= Min, V
IL
= Max
20
−0.4
20
µA
mA
µA
V
CC
= Max, V
I
= 7V
Min
Typ
(Note 4)
−1.5
DM54
DM74
DM54
DM74
DM74
2.4
2.4
3.4
V
3.1
0.25
0.35
0.4
0.5
0.4
0.1
mA
V
V
Max
Units
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4
’LS373 Electrical Characteristics
Symbol
I
CC
Parameter
Supply Current
(Continued)
over recommended operating free air temperature range (unless otherwise noted)
Conditions
V
CC
= Max, OC = 4.5V,
D
n
, Enable = GND
Min
Typ
(Note 4)
24
40
mA
Max
Units
’LS373 Switching Characteristics
at V
CC
= 5V and T
A
= 25˚C
From
Symbol
Parameter
(Input)
To
(Output)
t
PLH
Propagation Delay
Time Low to High
Level Output
t
PHL
Propagation Delay
Time High to Low
Level Output
t
PLH
Propagation Delay
Time Low to High
Level Output
t
PHL
Propagation Delay
Time High to Low
Level Output
t
PZH
Output Enable
Time to High
Level Output
t
PZL
Output Enable
Time to Low
Level Output
t
PHZ
Output Disable
Time from High
Level Output (Note 6)
t
PLZ
Output Disable
Time from Low
Level Output (Note 6)
Note 4:
All typicals are at V
CC
= 5V, T
A
= 25˚C.
Note 5:
Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 6:
C
L
= 5 pF.
R
L
= 667Ω
C
L
= 45 pF
Min
Max
C
L
= 150 pF
Min
Max
Units
Data
to
Q
Data
to
Q
Enable
to
Q
Enable
to
Q
Output
Control
to Any Q
Output
Control
to Any Q
Output
Control
to Any Q
Output
Control
to Any Q
25
ns
20
ns
36
50
ns
28
36
ns
30
36
ns
30
38
ns
18
27
ns
18
26
ns
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
Supply Voltage
High Level Input Voltage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Parameter
Min
4.5
2
0.7
−1
12
DM54LS374
Nom
5
Max
5.5
Min
4.75
2
0.8
−2.6
24
DM74LS374
Nom
5
Max
5.25
V
V
V
mA
mA
Units
5
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