CD74FCT821A
BiCMOS 10-BIT BUS-INTERFACE FLIP-FLOP
WITH 3-STATE OUTPUTS
SCBS731 − JULY 2000
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D BiCMOS Technology With Low Quiescent
Power
D Buffered Inputs
D Noninverted Outputs
D Input/Output Isolation From V
CC
D Controlled Output Edge Rates
D 48-mA Output Sink Current
D Output Voltage Swing Limited to 3.7 V
D SCR Latch-Up-Resistant BiCMOS Process
and Circuit Design
D Provide Extra Data Width Necessary for
Wider Address/Data Paths or Buses With
Parity
D Outputs Have Undershoot-Protection
Circuitry
D Buffered Control Inputs Reduce dc Loading
Effects
D Package Options Include Plastic
Small-Outline (M) Package and Standard
Plastic (EN) DIP
description
The CD74FCT821A is a 10-bit flip-flop that features 3-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.
This device uses a small-geometry BiCMOS technology. The output stage is a combination of bipolar and
CMOS transistors that limits the output high level to two diode drops below V
CC
. This resultant lowering of output
swing (0 V to 3.7 V) reduces power-bus ringing [a source of electromagnetic interference (EMI)] and minimizes
V
CC
bounce and ground bounce and their effects during simultaneous output switching. The output
configuration also enhances switching speed and is capable of sinking 48 mA.
The flip-flops enter data into their registers on the low-to-high transition of the clock (CLK). The Q outputs are
noninverted data. The output-enable (OE
) input controls the 3-state outputs and is independent of register
operation. When OE
is high, the outputs are in the high-impedance state.
The CD74FCT821A is characterized for operation from 0°C to 70°C.
FUNCTION TABLE
(each flip-flop)
INPUTS
OUTPUT
OE CLK D
Q
L ↑ H H
L ↑ LL
L LX Q
0
H X X Z
EN OR M PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
OE
1D
2D
3D
4D
5D
6D
7D
8D
9D
10D
GND
V
CC
1Q
2Q
3Q
4Q
5Q
6Q
7Q
8Q
9Q
10Q
CLK
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.
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.