SN74LS123DR

These d-c triggered multivibrators feature output pulse duration control by three methods. The basic pulse time is programmed by selection of external resistance and capacitance values (see typical application data). The '122 and 'LS122 have internal timing resistors that allow the circuits to be used with only an external capacitor, if so desired. Once triggered, the basic pulse duration 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. The 'LS122 and 'LS123 are provided enough Schmitt hysteresis to ensure jitter-free triggering from the B input with transition rates as slow as 0.1 millivolt per nanosecond. The Rint is nominally 10 kΩ for '122 and ‘LS122.

Key features

• DC-triggerable via active-high or active-low strobe logic inputs
• Retriggerable for ultra-long output pulses with up to 100% duty cycle
• Priority clear function for output pulse termination
• '122 and 'LS122 feature internal timing resistors
• Output pulse width adjustable via external components; external resistors improve pulse width accuracy, repeatability, and enable variable pulse width
• 'LS122 and 'LS123 incorporate sufficient Schmitt hysteresis for jitter-free triggering on slow-transition inputs