Fairchild N24C Dual 4-bit d-type transparent latches with 3-state output Datasheet

Revised July 2003
DM74AS873
Dual 4-Bit D-Type Transparent Latches
with 3-STATE Outputs
General Description
Features
These dual 4-bit registers feature totem-pole 3-STATE outputs designed specifically for driving highly-capacitive or
relatively 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 interface or pull-up components. They are particularly
attractive for implementing buffer registers, I/O ports, bidirectional bus drivers, and working registers.
■ Switching specifications at 50 pF
■ Switching specifications guaranteed over full temperature and VCC range
■ Advanced oxide-isolated, ion-implanted Schottky TTL
process
■ 3-STATE buffer-type outputs drive bus lines directly
■ Space Saving 300 Mil Wide Package
■ Bus structured pinout
The eight latches of the DM74AS873 are transparent Dtype 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.
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. That is, the old data can be retained or new
data can be entered even while the outputs are OFF.
The pinout is arranged to ease printed circuit board layout.
All data inputs are on one side of the package while all outputs are on the other side.
Ordering Code:
Order Number
DM74AS873NT
Package Number
N24C
Package Description
24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
© 2003 Fairchild Semiconductor Corporation
DS006330
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DM74AS873 Dual 4-Bit D-Type Transparent Latches with 3-STATE Outputs
December 1986
DM74AS873
Function Table
Logic Diagram
Inputs
Output
CLR
D
EN
OC
Q
X
X
X
H
Z
L
X
X
L
L
H
H
H
L
H
H
L
H
L
L
H
X
L
L
Q0
L = LOW State
H = HIGH State
X = Don’t Care
Z = High Impedance State
Q0 = Previous Condition of Q
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Supply Voltage
7V
Input Voltage
7V
Voltage Applied to Disabled Output
5.5V
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 tables are not guaranteed at the absolute maximum ratings.
The “Recommended Operating Conditions” table will define the conditions
for actual device operation.
0°C to +70°C
Operating Free Air Temperature Range
−65°C to +150°C
Storage Temperature Range
Typical θJA
47.0°C/W
N Package
Recommended Operating Conditions
Symbol
Parameter
Min
Nom
Max
Units
4.5
5
5.5
V
VCC
Supply Voltage
VIH
HIGH Level Input Voltage
VIL
LOW Level Input Voltage
0.8
V
IOH
HIGH Level Output Current
−15
mA
IOL
LOW Level Output Current
48
mA
tW
Pulse Width
2
Enable HIGH
5.5
Clear LOW
3.5
V
ns
tSU
Data Setup Time (Note 2)
2↓
tH
Data Hold Time (Note 2)
3↓
TA
Free Air Operating Temperature
0
ns
ns
°C
70
Note 2: The (↓) arrow indicates the negative edge of the enable is used for reference.
Electrical Characteristics
over recommended operating free air temperature range. All typical values are measured at VCC = 5V, TA = 25°C.
Symbol
Parameter
Conditions
VIK
Input Clamp Voltage
VCC = 4.5V, II = −18 mA
VOH
HIGH Level
VCC = 4.5V, VIL = Max
Output Voltage
IOH = Max
Min
2.4
IOH = −2 mA, VCC = 4.5V to 5.5V
VOL
II
LOW Level
VCC = 4.5V, VIH = 2V
Output Voltage
IOL = Max
Input Current at Max
VCC = 5.5V, VIH = 7V
Typ
Max
Units
−1.2
V
3.3
V
VCC −2
V
0.35
Input Voltage
0.5
V
0.1
mA
IIH
HIGH Level Input Current
VCC = 5.5V, VIH = 2.7V
20
µA
IIL
LOW Level Input Current
VCC = 5.5V, VIL = 0.4V
−0.5
mA
IO (Note 3)
Output Drive Current
VCC = 5.5V, VO = 2.25V
−112
mA
IOZH
OFF-State Output Current,
VCC = 5.5V, VIH = 2V
HIGH Level Voltage Applied
VO = 2.7V
50
µA
IOZL
OFF-State Output Current,
VCC = 5.5V, VIH = 2V
LOW Level Voltage Applied
VO = 0.4V
−50
µA
Supply Current
VCC = 5.5V
Outputs HIGH
68
110
mA
Outputs Open
Outputs LOW
67
109
mA
Outputs Disabled
80
129
mA
ICC
−30
Note 3: The output conditions have been chosen to produce a current that closely approximates one half of the true short circuit current, IOS.
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DM74AS873
Absolute Maximum Ratings(Note 1)
DM74AS873
Switching Characteristics
over recommended operating free air temperature range. All typical values are measured at VCC = 5V, TA = 25°C.
Symbol
Parameter
Conditions
From
To
Min
tPLH
tPHL
Propagation Delay Time
VCC = 4.5V to 5.5V
LOW-to-HIGH Level Output
RL = 500Ω
Propagation Delay Time
CL = 50 pF
HIGH-to-LOW Level Output
tPLH
Propagation Delay Time
LOW-to-HIGH Level Output
tPHL
Propagation Delay Time
HIGH-to-LOW Level Output
tPZH
Output Enable Time
Max
Units
Data
Any Q
3
6.5
ns
Data
Any Q
3
6
ns
Enable
Any Q
6
11.5
ns
Enable
Any Q
4
7.5
ns
Any Q
2
6.5
ns
Any Q
4
9.5
ns
Any Q
2
6.5
ns
Any Q
2
7.5
ns
Any Q
3
8.5
ns
Output Control
to HIGH Level Output
tPZL
Output Enable Time
Output Control
to LOW Level Output
tPHZ
Output Disable Time
Output Control
from HIGH Level Output
tPLZ
Output Disable Time
Output Control
from LOW Level Output
tPHL
Propagation Delay Time
Clear
HIGH-to-LOW Level Output
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DM74AS873 Dual 4-Bit D-Type Transparent Latches with 3-STATE Outputs
Physical Dimensions inches (millimeters) unless otherwise noted
24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Package Number N24C
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD
SEMICONDUCTOR CORPORATION. As used herein:
2. A critical component in any component of a life support
device or system whose failure to perform can be reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the
body, or (b) support or sustain life, and (c) whose failure
to perform when properly used in accordance with
instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the
user.
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