M74HC691(2001) データシートの表示（PDF） - STMicroelectronics
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M74HC691 Datasheet PDF : 17 Pages
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M74HC691
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
3 to 6
7, 14
15 to 18
1
2
11
8
9
19
10
20
SYMBOL
A to D
ENT, ENP
QA to QD
CCLR
CCK
R/C
RCLR
RCK
RCO
GND
VCC
NAME AND FUNCTION
Data Inputs
Enable Inputs
Data Outputs
Counter Clear (Active
LOW)
Counter Clock
Counter/Register Select
Register Clear (Active
LOW)
Register Clock
Ripple Counter Output
Ground (0V)
Positive Supply Voltage
TRUTH TABLE
INPUTS
OUTPUTS
CCLR LOAD ENP ENT CCK RCLR RCK R/C
X
X
X
X
X
X
X
X
L
X
X
X
X
X
X
L
H
L
X
X
X
X
L
G QA QB QC QD
X ZZZZ
L LLLL
L abcd
H
H
L
X
X
X
L
L
NO CHANGE
H
H
X
L
X
X
L
L
NO CHANGE
H
H
H
H
X
X
L
L
COUNT UP
H
X
X
X
X
X
L
L
NO CHANGE
X
X
X
X
X
L
X
H
L LLLL
X
X
X
X
X
H
H
L a’ b’ c’ d’
X
X
X
X
X
H
H
L
NO CHANGE
X : Don’t Care
Z : High Impedance
a-d : The level of steady state inputs at inputs A through D respectively.
a’-d’ : The level of steady state outputs at internal counter outputs a’ through qd’ respectively
RCO = QA · QB · QC · QD · ENT
FUNCTION
HIGH IMPEDANCE
CLEAR COUNTER
LOAD COUNTER
NO COUNT
NO COUNT
COUNT UP
NO COUNT
CLEAR REGISTER
LOAD REGISTER
NO LOAD
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