54abt646 National Semiconductor Corporation, 54abt646 Datasheet - Page 3

• Manufacturer Part Number: 54abt646
• Description: Octal Transceivers And Registers With Tri-state Outputs
• Manufacturer: National Semiconductor Corporation

Note 1: The data output functions may be enabled or disabled by various signals at the OE and DIR inputs. Data input functions are always enabled; i.e., data at
the bus pins will be stored on every LOW-to-HIGH transition of the appropriate clock inputs.
Connection Diagrams
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
N
OE
H
H
H
L
L
L
L
L
L
L
L
= LOW-to-HIGH Transition
DIR
X
X
X
H
H
H
H
L
L
L
L
CPAB
H or L
H or L
N
N
N
X
X
X
X
X
X
Inputs
Real Time Transfer
Real Time Transfer
A-Bus to B-Bus
B-Bus to A-Bus
CPBA SAB SBA A
H or L
H or L
FIGURE 1.
FIGURE 2.
N
N
N
X
X
X
X
X
X
DS100209-5
DS100209-6
H
H
X
X
X
L
L
X
X
X
X
(Continued)
X
X
X
X
X
X
X
H
H
L
L
Output
Input
Input Output
0
–A
Data I/O
(Note 1)
7
B
Input
Input
0
–B
7
3
Isolation
Clock A
Clock B
A
Clock A
A Register to B
Clock A
B
Clock B
B Register to A
Clock B
n
n
to B
to A
n
n
n
n
n
n
n
n
— Real Time (Transparent Mode)
— Real Time (Transparent Mode)
Data into A Register
Data into B Register
Data into A Register
Data into A Register and Output to B
Data into B Register
Data into B Register and Output to A
n
n
(Stored Mode)
(Stored Mode)
Function
Bus to Register
Register to Bus
Transfer from
Storage from
FIGURE 3.
FIGURE 4.
DS100209-7
DS100209-8
n
n
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