FreeLists / si-list / [SI-LIST] Re: terminator resistor

["Ched-Chang Chai" <ched_chang@xxxxxxxxxxx>]

Hi Gopalakrishnan,

If you are using source termination, the resistor value should be the 
difference between the trace characteristic impedance (Zo) and the driver 
output impedance (Zout):

Termination resistor = Zo - Zout.

Theoretically, the signals will be fully absorbed at the driver after one 
round trip time.

Anyway, I found that the output impedance is not a constant value.
From my experience, termination resistor with 22-47ohm will absorb most of 
the ringing.

--
Regards,
Chai


>From: "Gopalakrishnan Sethuraj" <gopalakrishnan.sethuraj@xxxxxxxxx>
>Reply-To: gopalakrishnan.sethuraj@xxxxxxxxx
>To: <weirsp@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
>Subject: [SI-LIST] terminator resistor
>Date: Mon, 2 Dec 2002 09:03:49 +0530
>
>hai
>
>how to find out the terminator resistor value when the ringing is occur in 
>high speed signal transmission line.could you let me know.is there any 
>specfic formula to find the terminator value?
>
>Thanks&Regards
>Gopalakrishnan.S


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