SN74LS423D.A中文资料德州仪器数据手册PDF规格书

Will Not Trigger from Clear

D.C Triggered from Actve-High or Active-

Low Gated Logic Inputs

Retriggerable for Very Long Output Pulses,

Up to 100% Duty Cycle

Overriding Clear Teminates Output Pulse

‘L§422 Has Internal Timing Resistor

description

The 'LS422 and ‘S423 are identical to ‘LS122 and

'LS123 except they cannot be triggered via clear.

These d-c triggered mulrivibrators feature output-pulse-

width control by three methods. The basic pulse time is

programmed by selection of external resistance and

capacitance values (see typical application datal. The

‘LS422 contains an internal timing resistor that allows

the circuits to be used with only an external capacitor, if

so desired. Once triggerad, the basic pulse width may be

extended by retriggering the gated low-level-active (Al

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.

The 'LS422 and LS423 have enough Schmitt hysteresis

to ensure jitter-free triggering from the B input with tran-

sition rates as slow as 0.1 millivolt per nanosecond. The

LS422 Ripe is nominally 10 k ohms.

The SN54LS422 and SN54LS423 are characterized for

operation over the full military temperature range of

—55°C to 125°C. The SN74LS422 and SN74L5423

are characterized for operation from 0°C to 70°C.