54ACTQ657
Quiet Series Octal Bidirectional Transceiver with 8-Bit
Parity Generator/Checker and TRI-STATE
Outputs
General Description
The ACTQ657 contains eight non-inverting buffers with
TRI-STATE outputs and an 8-bit parity generator/checker. In-
tended for bus oriented applications, the device combines
the '245 and the '280 functions in one package.
The ACTQ utilizes NSC Quiet Series technology to guaran-
tee quiet output switching and improved dynamic threshold
performance. FACT Quiet Series
TM
features GTO
TM
output
control and undershoot corrector in addition to a split ground
bus for superior performance.
Features
n
Guaranteed simultaneous switching noise level and
dynamic threshold performance
n
Combines the '245 and the '280 functions in one
package
n
Outputs source/sink 24 mA
n
'ACTQ has TTL-compatible inputs
n
Standard Microcircuit Drawing (SMD)
5962-92197
Logic Symbols
GTO
TM
is a trademark of National Semiconductor Corporation.
TRI-STATE
is a registered trademark of National Semiconductor Corporation.
FACT Quiet Series
TM
is a trademark of Fairchild Semiconductor Corporation.
IEEE/IEC
DS100244-1
DS100244-4
September 1998
54ACTQ657
Quiet
Series
Octal
Bidirectional
T
ransceiver
with
8-Bit
Parity
Generator/Checker
and
TRI-ST
A
T
E
Outputs
1998 National Semiconductor Corporation
DS100244
www.national.com
Connection Diagrams
Pin Names
Description
A
0
A
7
Data Inputs/TRI-STATE Outputs
B
0
B
7
Data Inputs/TRI-STATE Outputs
T/R
Transmit/Receive Input
OE
Enable Input
PARITY
Parity Input/TRI-STATE Output
ODD/EVEN
ODD/EVEN Parity Input
ERROR
Error TRI-STATE Output
Pin Assignment
for DIP and Flatpak
DS100244-2
Pin Assignment
for LCC
DS100244-3
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2
Functional Description
The Transmit/Receive (T/R) input determines the direction of
the data flow through the bidirectional transceivers. Transmit
(active HIGH) enables data from the A port to the B port; Re-
ceive (active LOW) enables data from the B port to the A
port.
The Output Enable (OE) input disables the parity and
ERROR outputs and both the A and B ports by placing them
in a HIGH-Z condition when the Output Enable input is
HIGH.
When transmitting (T/R HIGH), the parity generator detects
whether an even or odd number of bits on the A port are
HIGH and compares these with the condition of the parity se-
lect (ODD/EVEN). If the Parity Select is HIGH and an even
number of A inputs are HIGH, the Parity output is HIGH.
In receiving mode (T/R LOW), the parity select and number
of HIGH inputs on port B are compared to the condition of
the Parity input. If an even number of bits on the B port are
HIGH, the parity select is HIGH, and the PARITY input is
HIGH, then ERROR will be HIGH to indicate no error. If an
odd number of bits on the B port are HIGH, the parity select
is HIGH, and the PARITY input is HIGH, the ERROR will be
LOW indicating an error.
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3
Functional Description
(Continued)
Function Table
Number of
Inputs
Input/
Outputs
Inputs That
Output
Are High
OE
T/R
ODD/EVEN
Parity
ERROR
Outputs Mode
0, 2, 4, 6, 8
L
H
H
H
Z
Transmit
L
H
L
L
Z
Transmit
L
L
H
H
H
Receive
L
L
H
L
L
Receive
L
L
L
H
L
Receive
L
L
L
L
H
Receive
1, 3, 5, 7
L
H
H
L
Z
Transmit
L
H
L
H
Z
Transmit
L
L
H
H
L
Receive
L
L
H
L
H
Receive
L
L
L
H
H
Receive
L
L
L
L
L
Receive
Immaterial
H
X
X
Z
Z
Z
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = High Impedance
Function Table
Inputs
Outputs
OE
T/R
L
L
Bus B Data to Bus A
L
H
Bus A Data to Bus B
H
X
High-Z State
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
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