[SI-LIST] Re: Clock signal termination
- From: Vinu Arumugham <vinu@xxxxxxxxx>
- To: lucas_bossetti@xxxxxxxxxxx
- Date: Wed, 24 Apr 2002 09:45:11 -0700
With a 3.3V driver, the 178 ohm parallel term appears to produce a ~2.5V swing
at the receiver. Maybe the receiver is a 2.5V part.
Maybe they were trying to trim the duty cycle.
For the perfectionist, the series term may have to be 55-2*7=41 ohm instead of
36 ohm.
Thanks,
Vinu
Lucas Bossetti wrote:
> Hi all,
> In the schematic of an evaluation board I've seen some clock nets like that:
>
>
> parallel term to gnd R=178 ohm
>
> |
>
> |
> |---SERIES TERM 36ohm----Tline 55
> ohm------|----RECEIVER
> DRIVER 7 ohm--------|
> | --SERIES TERM 36ohm-----Tline 55
> ohm------|---RECEIVER
>
> |
>
> |
>
> parallel term to gnd R=178 ohm
>
> Can someone explain me why the value of the parallel term is 178 ohm?
> Any comment will be appreciate.
>
> Thanks in advance
> Lucas
>
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