HD74LS122 Datasheet, PDF (1/8 Pages) Hitachi Semiconductor – Retriggerable Monostable Multivibrators(with Clear)

HD74LS122
Retriggerable Monostable Multivibrator (with Clear)
REJ03D0428–0200
Rev.2.00
Feb.18.2005
This d-c triggered multivibrator features output pulse width control by three method. The basic pulse time is
programmed by selection of external resistance and capacitance values. The HD74LS122 has internal timing resistor
that allows the circuit to be used with only an external capacitor, if so desired. Once triggered, the basic pulse width
may be extended by retriggering the gated low-level -active (A) or high-level active (B) inputs or be reduced by use of
the overriding clear. Figure 1 illustrates pulse control by retriggering and early clear. This device is provided enough
Schmitt hysteresis to ensure jitter-free triggering from the B input with transition rates as slow as 0.1 mV/ns.
A = "L"
Clear = "H"
B
Q
A = "L"
B
Retrigger Pulse
"H"
"L"
t_w + t_PLH
"H"
t_w
"L"
Output without
retrigger
"H"
"L"
Clear
"H"
"L"
"H"
Q
"L"
Output without
clear
Figure 1
Typical Input / Output Pulse
Rev.2.00, Feb.18.2005, page 1 of 7