• Functionally Equivalent to AMD’s AM29823
• Provide Extra Data Width Necessary for
Wider Address/Data Paths or Buses With
• Outputs Have Undershoot-Protection
• Power-Up High-Impedance State
• Buffered Control Inputs to Reduce
dc Loading Effects
• Package Options Include Plastic
Small-Outline (DW) Packages, Ceramic
Chip Carriers (FK), and Standard Plastic
(NT) and Ceramic (JT) 300-mil DIPs
These 9-bit flip-flops feature 3-state outputs
designed specifically for driving highly capacitive
or relatively low-impedance loads. These devices
are particularly suitable for implementing wider
buffer registers, I/O ports, bidirectional bus
drivers, parity bus interfacing, and working
With the clock-enable (CLKEN) input low, the nine
D-type edge-triggered flip-flops enter data on the
low-to-high transitions of the clock (CLK) input.
Taking CLKEN high disables the clock buffer,
latching the outputs. The SN54AS823A and
SN74AS823A have noninverting data (D) inputs
and the SN74AS824A has inverting (D) inputs.
Taking the clear (CLR) input low causes the nine
Q outputs to go low independently of the clock.
A buffered output-enable (OE) input can be used
to place the nine outputs in either a normal logic
state (high or low logic level) or the high-
impedance state. In the high-impedance state, the
outputs neither load nor drive the bus lines
significantly. The high-impedance state and
increased drive provide the capability to drive bus
lines without interface or pullup components.
OE does not affect the internal operation of the
flip-flops. Old data can be retained or new data
can be entered while the outputs are in the
The SN54AS823A is characterized for operation
over the full military temperature range of – 55°C
to 125°C. The SN74AS823A and SN74AS824A
are characterized for operation from 0°C to 70°C.
SN54AS823A, SN74AS823A, SN74AS824A
9-BIT BUS-INTERFACE FLIP-FLOPS
WITH 3-STATE OUTPUTS
SDAS231A – JUNE 1984 – REVISED AUGUST 1995
SN54AS823A . . . JT PACKAGE
SN74AS823A . . . DW OR NT PACKAGE
SN54AS823A . . . FK PACKAGE
4 3 2 1 28 27 26
12 13 14 15 16 17 18
SN74AS824A . . . DW OR NT PACKAGE
NC – No internal connection
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright © 1995, Texas Instruments Incorporated