SN54ABT16821, SN74ABT16821
20-BIT BUS-INTERFACE FLIP-FLOPS
WITH 3-STATE OUTPUTS
SCBS216B – JUNE 1992 – REVISED JANUARY 1997
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Members of the Texas Instruments
Widebus
™
Family
State-of-the-Art
EPIC-
ΙΙ
B
™
BiCMOS Design
Significantly Reduces Power Dissipation
ESD Protection Exceeds 2000 V Per
MIL-STD-883, Method 3015; Exceeds 200 V
Using Machine Model (C = 200 pF, R = 0)
Typical V
OLP
(Output Ground Bounce) < 1 V
at V
CC
= 5 V, T
A
= 25°C
Distributed V
CC
and GND Pin Configuration
Minimizes High-Speed Switching Noise
Flow-Through Architecture Optimizes PCB
Layout
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
SN54ABT16821 . . . WD PACKAGE
SN74ABT16821 . . . DGG OR DL PACKAGE
(TOP VIEW)
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.
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.
1OE
1Q1
1Q2
GND
1Q3
1Q4
V
CC
1Q5
1Q6
1Q7
GND
1Q8
1Q9
1Q10
2Q1
2Q2
2Q3
GND
2Q4
2Q5
2Q6
V
CC
2Q7
2Q8
GND
2Q9
2Q10
2OE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
1CLK
1D1
1D2
GND
1D3
1D4
V
CC
1D5
1D6
1D7
GND
1D8
1D9
1D10
2D1
2D2
2D3
GND
2D4
2D5
2D6
V
CC
2D7
2D8
GND
2D9
2D10
2CLK
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
the bus lines significantly. The high-impedance state and increased drive provide the capability to drive bus lines
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
CC
through a pullup
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.
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.
POST OFFICE BOX 655303
Copyright
©
1997, Texas Instruments Incorporated
•
DALLAS, TEXAS 75265
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TI [ TEXAS INSTRUMENTS ]
