RE: [SI-LIST] : [Fwd: Majordomo results: Looking for highspeedbuffer parts]

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From: Craig Callen (ccallen@ibnets.com)
Date: Fri Nov 05 1999 - 07:35:26 PST


Jason,

Take a look at the MPC940L clock driver from Motorola. It has a
3.3V core and the IO can be either 3.3V or 2.5V. You will probably
need to use 3.3V io to get the extra drive to drive those
edge rates. It has max. output to output skew of 150ps.
It supposedly will work up to 250MHz, which I question especially
from a thermal standpoint but the fastest I have tested the part is 125Mhz.
This is not pretty but it is better than nothing and should also
do a better job than a 244 buffer. I dont know how many clocks you need
to fan out but if you need a 1:1 clock buffer than this is probably
overkill since it is 1:18. It can receive a single ended or differential
clock input.

Craig

> -----Original Message-----
> From: owner-si-list@silab.eng.sun.com
> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Jason Zheng
> Sent: Friday, November 05, 1999 12:51 AM
> To: si-list@silab.eng.sun.com
> Subject: Re: [SI-LIST] : [Fwd: Majordomo results: Looking for
> highspeedbuffer parts]
>
>
>
> > Be careful if you intend to use an inverter as a clock buffer. The alvc
> > stuff is pretty fast, but not nearly fast enough for your needs. That
> > particular part is about 4nS spec into a heavy load, and a
> minimum Tpd spec
> > of 1nS. At 240MHz Tpd alone is 50% of your cycle interval. That
> > translates to linear amplifier. I don't know who did your ASIC's or the
> > system design, but 240MHz at SSTTL is going to be very hard to do.
>
> Thank you for your help!
>
> Our ASIC is committed already. We are designing the prototype
> board to bring it up. For now, it only needs to work at
> room temperature (instead of the worst case conditions). If
> the IDT74ALVC16244A part (or GAL16LV8) is not fast enough for
> room temperature application, do you know of any other part that
> might do? We will have adjustable delay lines to tune the skew
> among ASICs, so the skew is not the prob. But it needs
> to drive 100 or 50 ohm transmission lines for TTL/CMOS levels.
>
> Thanks again!
>
> -Jason
>
> >
> > Regards,
> >
> > Steve.
>
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