From: Bo ([email protected])
Date: Thu Oct 26 2000 - 11:22:31 PDT
Hi Ken,
I have used several different hstl I/O pads. Depending on the quality of I/O
pads you are using you might be able to get away with series termination on the
driver. I have used several HSTL technologies that could not do series
termination in the worst case conditions. The recommended way is to use 50 Ohm
parallel termination at the receiver(this will typically give you a good clean
signal). Try other values for the resistor that will change your power supply
requirements (which may help you to get your power supply cicruit to work).
One other note, make sure that your 0.75V power supply is really clean. This
power supply will go to the comparator inside of the pad. You can imagine what
will happen if this voltage is not constant(I had this problem on my chip that
was using HSTL pads).
Regards,
Bo
p.s. From what I can guess you are probably using IBM's HSTL I/O pads(those are
commonly used by people at your company). Am I correct?
--- Ken Church <[email protected]> wrote:
> Hey,
>
> Does anybody have any experience with HSTL Class 1 termination? The
> problem is determining a method of generating a good .75V source that
> can source and sink current. Has this typically been a problem? Or is
> there already a neat and cleaver way that is commonly used?
>
> Regards,
>
> Ken Church
>
>
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