SN54ABT16821, SN74ABT16821
20-BIT BUS-INTERFACE FLIP-FLOPS
WITH 3-STATE OUTPUTS
SCBS216B – JUNE 1992 – REVISED JANUARY 1997
SN54ABT16821 . . . WD PACKAGE
SN74ABT16821 . . . DGG OR DL PACKAGE
(TOP VIEW)
Members of the Texas Instruments
Widebus Family
State-of-the-Art EPIC-ΙΙB BiCMOS Design
Significantly Reduces Power Dissipation
1OE
1Q1
1Q2
GND
1Q3
1Q4
1CLK
1D1
1D2
GND
1D3
1D4
1
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
ESD Protection Exceeds 2000 V Per
MIL-STD-883, Method 3015; Exceeds 200 V
Using Machine Model (C = 200 pF, R = 0)
2
3
4
Typical V
(Output Ground Bounce) < 1 V
5
OLP
at V
= 5 V, T = 25°C
6
CC
A
V
V
7
Distributed V
Minimizes High-Speed Switching Noise
and GND Pin Configuration
CC
CC
CC
1Q5
1Q6
1Q7
GND
1Q8
1Q9
1Q10
2Q1
2Q2
2Q3
GND
2Q4
2Q5
2Q6
1D5
1D6
1D7
GND
1D8
1D9
1D10
2D1
2D2
2D3
GND
2D4
2D5
2D6
8
9
Flow-Through Architecture Optimizes PCB
Layout
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
High-Drive Outputs (–32-mA I
,
OH
64-mA I
)
OL
Package Options Include Plastic Thin
Shrink Small-Outline (DGG), 300-mil Shrink
Small-Outline (DL) Packages and 380-mil
Fine-Pitch Ceramic Flat (WD) Package
Using 25-mil Center-to-Center Spacings
description
These 20-bit flip-flops feature 3-state outputs
designed specifically for driving highly capacitive
or relatively low-impedance loads. They are
particularly suitable for implementing wider buffer
registers, I/O ports, bidirectional bus drivers with
parity, and working registers.
V
V
CC
CC
2Q7
2Q8
2D7
2D8
GND 25
32 GND
2Q9
2Q10
2OE
2D9
2D10
2CLK
26
27
28
31
30
29
The ’ABT16821 can be used as two 10-bit
flip-flops or one 20-bit flip-flop. The 20 flip-flops
are edge-triggered D-type flip-flops. On the
positive transition of the clock (CLK) input, the
device provides true data at the Q outputs.
A buffered output-enable (OE) input can be used to place the ten outputs in either a normal logic state (high
or low logic level) or a high-impedance state. In the high-impedance state, the outputs neither load nor drive
thebuslinessignificantly. Thehigh-impedancestateandincreaseddriveprovidethecapabilitytodrivebuslines
without need for 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 high-impedance state.
To ensure the high-impedance state during power up or power down, OE should be tied to V through a pullup
CC
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
The SN54ABT16821 is characterized for operation over the full military temperature range of –55°C to 125°C.
The SN74ABT16821 is characterized for operation from –40°C to 85°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Widebus and EPIC-ΙΙB are trademarks of Texas Instruments Incorporated.
Copyright 1997, Texas Instruments Incorporated
UNLESS OTHERWISE NOTED this document contains PRODUCTION
DATA information 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.
1
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