74LCX646 Datasheet, PDF (2/10 Pages) Fairchild Semiconductor – Low Voltage Octal Transceiver/Register with 5V Tolerant Inputs and Outputs

Logic Symbols
IEEE/IEC
Truth Table
(Note 2)
OE
Inputs
Data I/O
DIR CPAB CPBA SAB SBA A₀–A₇ B₀–B₇
Function
H
X H or L H or L X
X
Isolation
H
H
 X
X
X
 X
X
X
X Input Input Clock A_n Data into A Register
X
Clock B_n Data into B Register
L
L
H
X
X
 H
X
L
L
X
A_n to B_n—Real Time (Transparent Mode)
X Input Output Clock A_n Data into A Register
L
L
 ^{H H or L X}
H
X
H
H
X
X
A Register to B_n (Stored Mode)
Clock A_n Data into A Register and Output to B_n
L
L
L
L
X
X
X
 X
X
L
B_n to A_n—Real Time (Transparent Mode)
L Output Input Clock B_n Data into B Register
L
L
X H or L X
H
L
L
 X
X
H
B Register to A_n (Stored Mode)
Clock B_n Data into B Register and Output to A_n
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
= LOW-to-HIGH Transition
Note 2: 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.
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