74lcx646 STMicroelectronics, 74lcx646 Datasheet - Page 3

• Manufacturer Part Number: 74lcx646
• Description: Low Volt. Cmos Octal Bus Transceiver/register With 5 Volt Tolerant Inputs And Outputs 3-state
• Manufacturer: STMicroelectronics

Table 3: Truth Table
X : Don’t Care
Z : High Impedance
Qn: The data stored to the internal flip-flops by most recent low to high transition of the clock inputs
* : The data at the A and B bus will be stored to the internal flip-flops on every low to high transition of the clock inputs.
G
H
L
L
DIR CAB CBA SAB SBA
H
X
L
X*
X*
X*
X*
X
X
X
X*
X*
X*
X*
X
X
X
X
X
H
H
X
X
X
X
L
L
X
X
X
X
X
X
H
H
L
L
OUTPUTS
INPUTS
INPUTS
INPUTS
Qn
A
H
H
X
H
H
H
H
Z
L
L
L
L
L
L
OUTPUTS The A bus are inputs and the B bus are outputs
INPUTS
INPUTS
INPUTS
Qn
B
H
H
H
H
H
X
H
Z
L
L
L
L
L
L
Both the A bus and the B bus are inputs
The Output functions of the A and B bus are disabled
Both the A and B bus are used as inputs to the internal
flip-flops. Data at the bus will be stored on low to high
transition of the clock inputs.
The data at the A bus are displayed at the B bus
The data at the A bus are displayed at the B bus. The
data of the A bus are stored to internal flip-flop on low
to high transition of the clock pulse
The data stored to the internal flip-flop are displayed at
the B bus.
The data at the A bus are stored to the internal flip-flop
on low to high transition of the clock pulse. The states
of the internal flip-flops output directly to the B bus.
The B bus are inputs and the A bus are outputs.
The data at the B bus are displayed at the A bus
The data at the B bus are displayed at the A bus. The
data of the B bus are stored to the internal flip-flop on
low to high transition of the clock pulse.
The data stored to the internal flip-flops are displayed
at the A bus
The data at the B bus are stored to the internal flip-flop
on low to high transition of the clock pulse. The states
of the internal flip-flops output directly to the A bus.
FUNCTION
M74LCX646
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