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IN74HC123

ETC
Part Number IN74HC123
Manufacturer ETC
Description DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATOR
Published Sep 26, 2005
Detailed Description IN74HC123 DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATOR The IN74HC123 is identical in pinout to the LS/ALS123. The device...
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IN74HC123
IN74HC123

Overview
IN74HC123 DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATOR The IN74HC123 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 RX and capacitor CX.
Taking CRL 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 LOGIC DIAGRAM • • • • ORDERING INFORMATION IN74HC123N Plastic IN74HC123D SOIC TA = -55° to 125° C for all packages PIN ASSIGNMENT PIN 16 =VCC PIN 8 = GND FUNCTION TABLE Inputs Outputs Note A B CRL Q Q H H Output Enable X L H L* H* Inhibit * * H X H L H Inhibit L H Output Enable L H Output Enable X X L L H Inhibit X = don’t care * - except for monostable period Note (1) CX, RX, DX are external components.
(2) DX is a clamping diode.
The external capacitor is charged to VCC in the stand-by state, i.
e.
no trigger.
When the supply voltage is turned off CX is discharged mainly through an internal parasitic diode.
If CX is sufficiently large and VCC 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 VCC 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.
1 IN74HC123 MAXIMUM RATINGS* Symbol Parameter Value Unit VCC DC Supply Voltage...


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