RE: [SI-LIST] : Excessive clock overshoot

Andrew Ingraham ([email protected])
Wed, 13 May 1998 19:15:07 -0400

> 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.

>Any ideas on what could be causing this?

Sounds like a reflection that adds to the clock one cycle later. The
first clock cycle is probably OK, then it builds up over the next few
cycles. The clock line is resonant near a harmonic of 45MHz.