DM74AS873 Dual 4-Bit D-Type Transparent Latches with 3-STATE Outputs
December 1986
Revised July 2003
DM74AS873
Dual 4-Bit D-Type Transparent Latches
with 3-STATE Outputs
General Description
These dual 4-bit registers feature totem-pole 3-STATE out-
puts 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 driv-
ing 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, bidi-
rectional bus drivers, and working registers.
The eight latches of the DM74AS873 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.
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-imped-
ance 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 out-
puts are on the other side.
Features
s
Switching specifications at 50 pF
s
Switching specifications guaranteed over full tempera-
ture and V
CC
range
s
Advanced oxide-isolated, ion-implanted Schottky TTL
process
s
3-STATE buffer-type outputs drive bus lines directly
s
Space Saving 300 Mil Wide Package
s
Bus structured pinout
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 鈥淴鈥?to the ordering code.
Connection Diagram
漏 2003 Fairchild Semiconductor Corporation
DS006330
www.fairchildsemi.com
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