Datasheet
2
Functional Diagram
MODE SELECT FUNCTION TABLE THREE-STATE I/O PORT OPERATING MODE
FUNCTION
INPUTS INPUTS/OUTPUTS
OE1 OE2 S0 S1 Qn (REGISTER) I/O0 --- I/O7
Read Register L L L X L L
L
LL
XH H
LLXL L L
LLXL H H
Load Register X X H H Qn = I/On I/On = Inputs
Disable I/O H X X X X (Z)
XHXX X (Z)
TRUTH TABLE
FUNCTION
INPUTS REGISTER OUTPUTS
MR CP S0 S1 DS0 DS7 I/On Q0 Q1 --- Q6 Q7
RESET (CLEAR) L XXXXXXLL---LL
Shift Right H ↑ hl lXXLq
0
--- q
5
q
6
H ↑ hlhXXHq
0
--- q
5
Q6
Shift Left H ↑ lhXlXq
1
q2 --- q
7
L
H ↑ lhXhXq
1
q
2
--- q
7
H
Hold (Do Nothing) H ↑ l l XXXq
0
q
1
--- q
6
q
7
Parallel Load H ↑ hhXXlLL---LL
H ↑ h h X X h H H --- H H
H = Input Voltage High Level, h = Input voltage high one set-up timer prior clock transition; L = Input Voltage Low Level; l = Input voltage
low one set-up time prior to clock transition; qn = Lower case letter indicates the state of the reference output one set-up time prior to clock
transition; X - Voltage level on logic status don’t care; Z = Output in high impedance state, ↑ = Low to High Clock Transition.
I/O
THREE-STATE
OUTPUTS
I/O
THREE-STATE
OUTPUTS
SHIFT
REGISTER
MODE SELECTION
CP OE1 OE2 MR
12 2 3 9
20
V
CC
7
6
5
4
8
1
I/O
0
Q0
S0
STANDARD
OUTPUT
I/O
2
I/O
4
I/O
6
BUS LINE
OUTPUTS
GND
10 11 18
DS0 DS7
13
14
15
16
17
19
I/O
1
Q7
S1
STANDARD
OUTPUT
I/O
3
I/O
5
I/O
7
BUS LINE
OUTPUTS
THREE-
STATE
CONTROL
CD54HC299, CD74HC299, CD54HCT299, CD74HCT299