SDLS043 - DECEMBER 1983 - 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 '122 or 'LS122, conntactRint to VCC. For improved pulse duration accuracy and repeatability, connectan external resistor between Rext/Cext and VCC with Rint open-circuited. To obtain variable pulse durations, connect an external variableresistance between Rint or Rext/Cext andVCC.
These d-c triggered multivibrators feature output pulse-duration controlby three methods. The basic pulse time is programmed by selection of externalresistance and capacitance values (see typical application data). The '122and 'LS122 have internal timing resistors that allow the circuits to be usedwith only an external capacitor, if so desired. Once triggered, the basicpulse 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 overridingclear. Figure 1 illustrates pulse control by retriggering and early clear.
The 'LS122 and 'LS123 are provided enough Schmitt hysteresis to ensurejitter-free triggering from the B input with transition rates as slow as 0.1millivolt per nanosecond.
The Rint is nominally 10 k
for '122 and 'LS122.
View more information about generic part numbers:SN54122, SN54123, SN54LS123, SN74122, SN74123, SN74130, SN74LS122, SN74LS123
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