SN74LV123A / about Output Pulse Duration

Table 7.3 of the datasheet puts no upper limit on the timing resistance, and no restriction on the timing capacitance. Using a sufficiently large resistor and capacitor will work (e.g., 1 MΩ and 1 µF will result in 1 s).

If you want the timing to be very precise, consider a low-tolerance capacitor type with low leakage current/high isolation resistance, such as PP foil (MKP).

Hi Clemens - san,

Thank you for the reply. In the case of 30s duration, please let me know what is the recommended parts and the value for Rext, Cext.

Best Regards,

Kato

     Hi,

      I designed a circuit in Tina by using SN74LV123A monostable multivibrator. In this design I expect 110ms tw at the output pin(Q) of SN74LV123A. According to tw=K*R*C formula I used 11k resistor and 10u capacitor to obtain 110ms tw at the output. But I obtain approximately 140 ms at the output and this value is not useful for my design. I used below formula to calculate tw value. 

    I used 2 SN74LV123A in this design. U1 is negative edge detector and U5 is positive edge detector.At the outputs(DIR and ROT) I expect 110ms pulse.

      According to simation result I obtain approximately 140 ms pulse duration.Could you help me how I can obtain 110 ms pulse at the outputs?