Regards, Fabrizio Zanella.
From: "D. C. Sessions" <email@example.com>, on 5/13/98 5:23 PM:
To: smtp@Eng@EMCHOP1["SI-List" <si-list@silab.Eng.Sun.COM>]
Cc: smtp@Eng@EMCHOP1["SI-List" <si-list@silab.Eng.Sun.COM>]
fabrizio zanella wrote:
> 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
> 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
> 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,
> do they have an explanation for it.
> Any ideas on what could be causing this?
1) Is the line unterminated?
2) Is the loaded one-way delay anything near 2.7ns?
-- D. C. Sessions firstname.lastname@example.org