SN74AS1821 Datasheet, PDF (1/5 Pages) Texas Instruments – 10-BIT BUS INTERFACE FLIP-FLOPS WITH 3-STATE OUTPUTS

SN74AS1821
10ĆBIT BUS INTERFACE FLIPĆFLOPS WITH 3ĆSTATE OUTPUTS
• Center V_CC and GND Configuration Provides
Minimum Lead Inductance in High Current
Switching Applications
• Provides Extra Data Width Necessary for Wider
Address/Data Paths or Buses with Parity
• Outputs Have Undershoot Protection Circuitry
• Power-Up High-Impedance State
• Package Options include Plastic DIPS. Use the
’AS821 for Plastic and Ceramic Chip Carriers
and “Small Outline” Package Options.
• Buffered Control inputs to Reduce DC Loading
Effects
description
This 10-bit flip-flop device features three-state
outputs designed specifically for driving highly
capacitive or relatively low-impedance loads. It is
particularly suitable for implementing wider buffer
registers, I/O ports, bidirectional bus drivers with
parity, and working registers. The ten flip-flops are
edge-triggered D-type flip-flops. On the positive
transition of the clock, the Q outputs on the
’AS1821 will be true.
A buffered output-control input can be used to
place the ten outputs in either a normal logic state
(high or low levels) or a 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 the bus lines in a
bus-organized system without need for interface
or pull-up components. The output control (OC)
does not affect the internal operation of the
flipflops. Old data can be retained or new data can
be entered while the outputs are in the
high-impedance state.
The SN74AS1821 is characterized for operation
from 0°C to 70°C.
NT PACKAGE
(TOP VIEW)
SDAS131 − APRIL 1987
5Q ₁
4Q ₂
3Q ₃
2Q ₄
1Q ₅
V_{CC 6}
OC 7
1D 8
2D 9
3D 10
4D 11
5D 12
24 ^6Q
23 ^7Q
22 ^8Q
21 ^9Q
20 ^10Q
19 ^CLK
18 GND
17 10D
16 9D
15 8D
14 7D
13 6D
FUNCTION TABLE
(each flip-flop)
INPUTS
OC CLK D
L↑ H
L↑
L
LL
X
HX X
OUTPUT
Q
H
L
QO
Z
logic symbol^†
(7)
OC
(19)
CLK
(8)
1D
(9)
2D
(10)
3D
(11)
4D
(12)
5D
(13)
6D
(14)
7D
(15)
8D
(16)
9D
(17)
10D
EN
C1
1D
(5)
1Q
(4)
2Q
(3)
3Q
(2)
4Q
(1)
5Q
(24)
6Q
(23)
7Q
(22)
8Q
(21)
9Q
(20)
10Q
† _{This symbol is in accordance with ANSI/IEEE Std 91-1984 and}
IEC Publication 617-12.
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.
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
Copyright  1987, Texas Instruments Incorporated
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