KK74HC123A Datasheet, PDF (1/7 Pages) KODENSHI KOREA CORP. – Dual Retriggerable Monostable Multivibrator

TECHNICAL DATA
KK74HC123A
Dual Retriggerable Monostable
Multivibrator
The KK74HC123A is identical in pinout to the LS/ALS123. The
device inputs are compatible with standard CMOS outputs; with pullup
resistors, they are compatible with LS/ALSTTL outputs.
There are two trigger inputs, A INPUT (negative edge) and
B INPUT (positive edge). These inputs are valid for rising/falling signals.
The device may also be triggered by using the CLR input (positive-
edge) because of the Schmitt-trigger input; after triggering the output
maintains the MONOSTABLE state for the time period determined by the
external resistor R_X and capacitor C_X. Taking CLR low breaks this
MONOSTABLE STATE. If the next trigger pulse occurs during the
MONOSTABLE period it makes the MONOSTABLE period longer.
• Outputs Directly Interface to CMOS, NMOS, and TTL
• Operating Voltage Range: 3.0 to 6.0 V
• Low Input Current: 1.0 µA
• High Noise Immunity Characteristic of CMOS Devices
ORDERING INFORMATION
KK74HC123AN Plastic
KK74HC123AD SOIC
T_A = -55° to 125° C for all packages
PIN ASSIGNMENT
LOGIC DIAGRAM
PIN 16 =V_CC
PIN 8 = GND
Note
(1) C_X, R_X, D_X are external components.
(2) D_X is a clamping diode.
The external capacitor is charged to V_CC in the stand-by
state, i.e. no trigger. When the supply voltage is turned off
C_X is discharged mainly through an internal parasitic diode.
If C_X is sufficiently large and V_CC decreases rapidy, there
will be some possibility of damaging the I.C. with a surge
current or latch-up. If the voltage supply filter capacitor is
large enough and V_CC decrease slowly, the surge current is
automatically limited and damage the I.C. is avoided. The
maximum forward current of the parasitic diode is
approximately 20 mA.
FUNCTION TABLE
Inputs
A B CLR
HH
Outputs
QQ
XL
H
L^* H^*
HX
H
L^* H^*
L
H
LH
XX L L H
X = don’t care
* _{- except for monostable period}
Note
Output
Enable
Inhibit
Inhibit
Output
Enable
Output
Enable
Inhibit
1