WS74HC595
FUNCTIONAL DESCRIPTION
1.
Truth Table
Inputs
Function
SER
SRCK
SRCL
RCK
OE
X
X
X
L
X
X
X
↑
X
X
L
X
X
X
H
L
X
Outputs Q1-Q8 are disabled.
Outputs Q1-Q8 are enabled.
Shift register is cleared.
H
X
X
First stage of the shift register goes low.
Other stages store the data of previous stage, respectively.
H
↑
H
X
X
First stage of the shift register goes high.
Other stages store the data of previous stage, respectively.
X
X
X
↑
X
Shift-register data is stored in the latch.
H = High Level (steady state). L= Low Level (steady state)
X = Irrelevant (don’t care)
↑=
Transition from low to high level.
2. Logic Waveform
SRCK
SER
RCK
SRCL
OE
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q8'
Note:
implies that the outputs are in 3-state mode.
2
WINGS [ WING SHING COMPUTER COMPONENTS ]
