> How do you calculate the out pulse duration?  In my example, I have a
> 0.01uf cap and a 15Kohm resistor.  The book I am reading states that the
> pulse is 200us, however when I calculate the RC time constant at the
> first time interval, I only get 150us.

The time constant is indeed 10nF x 15Kohm = 150uS.  This is the time it
takes for the exponential to reach (1 - 1/e) = 62% of its final value.  Your
signal starts out at 5V and exponentially decays towards 0.  After 150uS, it
will therefore be at 5V * 1/(e**1) = 1.8V, after two time constants (300uS)
it will be at 5V * 1/(e**2) = 68mV, etc.  The pulse duration depends on
where the input threshold voltage of the second inverter is.  This is
usually specified over a considerable range, so "around 200uS" is probably
as good an estimate as anything since the variation is so high.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body