It is a monostable trigger.
that
RxCx
(7, 15)
and
Cx
build
(6, 14)
Timing resistors and capacitors,
I.e. after deciding to trigger.
Q
The width of a single pulse generated by the terminal.
Rbar
(3, 1 1)
Is a low reset zero,
It is high and has not been reset to zero.
aba
( 1,9)
Is a falling edge trigger input,
get through
aba
Triggered by a negative pulse,
Stay high when not in use.
B
(2, 10)
Is a rising edge trigger input,
get through
B
Triggered by a positive pulse,
Put it down when not in use.
Q
(5, 13)
and
Qbar
(4, 12)
Output positive and negative timing monopulse respectively.
The function of monostable trigger in the device is to restore the pre-trigger state by maintaining the peripheral resistance and capacitance for a given time, no matter how long the trigger signal lasts. Peripheral resistance and capacitance determine the monostable time, because the trigger is triggered by an edge, a rising edge or a falling edge. The difference between the retriggerable monostable is that when the monostable triggered last time does not return to the pre-trigger state and there is a trigger signal, the retriggerable monostable will continue to maintain the resistance and capacitance of the monostable for a given time at the trigger edge, while the monostable ignores the trigger signal after flipping. This chip can also be used as a multivibrator.
74HC 123 monostable trigger. It has two inputs, A active low and B active high. There are two kinds of outputs, just the opposite. Using external resistor and capacitor as timing element, the time can be decided by itself, which is better than 74LS circuit.
The monostable flip-flop 74HC 123 and peripheral circuits are used to realize this function. 74HC 123 is a double trigger monostable, and the width of its output pulse mainly depends on the timing resistor R and the timing capacitor C. The pulse width is calculated as the product of the capacitance value and the resistance value, that is, WP=R? C, in the actual design, R=5kW, C=80pF, the output pulse width is 400ns, and the amplitude is about 5V. The emitter-following output circuit of pulse fast edge amplification is mainly used to accelerate the amplification of the shaped and broadened trigger pulse, so as to obtain a pulse signal with higher amplitude and faster rising edge to trigger the field effect transistor 2SC3306.