[SI-LIST] : Excessive clock overshoot
fabrizio zanella (email@example.com)
Wed, 13 May 98 16:16:51 -0400
I have a question regarding an FCT clock (TTL levels) driving a heavily
loaded backplane. On the driver pin we see excessive overshoot on the L-H
transition which increases as we increase the clock frequency. This
overshoot goes from 5V at 33MHz to 6.5-7.0V at 45MHz. The stub impedance
is 75 ohms, backplane impedance 25 ohms loaded. There is a clamping diode
on the H-L side but not on the L-H. The H-L side does not have any
I have asked the manufacturer and they have never seen this phenomena, nor
do they have an explanation for it.
Any ideas on what could be causing this?
thanks and regards,