SDLS175 - JANUARY 1980 - REVISED MARCH 1988
PRODUCTION DATA documents contain information current as of publicationdate. Products conform to specifications per the terms of Texas Instrumentsstandard warranty. Production processing does not necessarily include testingof all parameters.
An external timing capacitor may be connected between Cext and Rext/Cext (positive). To use the internal timing resistor of 'LS422, connect Rint to VCC. For improved pulse width accuracy and repeatability, connectan external resistor between Rext/Cext and VCC with Rint open-circuited. To obtain variable pulse widths, connect an external variableresistance between Rint or Rext/Cext andVCC.
The 'LS422 and 'LS423 are identical to 'LS122 and 'LS123 except they cannotbe triggered via clear.
These d-c triggered multivibrators feature output-pulse-width control bythree methods. The basic pulse time is programmed by selection of externalresistance and capacitance values (see typical application data). The 'LS422contains an internal timing resistor that allows the circuits to be used withonly an external capacitor, if so desired. Once triggered, the basic pulsewidth 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 illustratespulse control by retriggering and early clear.
The 'LS422 and 'LS423 have enough Schmitt hysteresis to ensure jitter-freetriggering from the B input with transition rates as slow as 0.1 millivoltper nanosecond. The 'LS422 Rint is nominally 10 k ohms.
The SN54LS422 and SN54LS423 are characterized for operation over the fullmilitary temperature range of -55°C to 125°C. The SN74LS422 and SN74LS423are characterized for operation from 0°C to 70°C.
View more information about generic part numbers:SN74LS422, SN74LS423
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