Re: [SI-LIST] : Terminating a bidirectional bus

Arrigo Benedetti (arrigo@vision.caltech.edu)
03 May 1999 12:49:16 -0700

Shayle Hirschman <shayle@mho.net> writes:

> May I add to your question what would the answer be if the FPGA and RAM are
> 3.3 v devices vs. 5 v devices? Would less of a voltage swing reduce the
> need for termination, especially, as you are asking, on the data lines?
>
> Shayle

These are 3.3V devices and from some simulations that one of our students is
doing with Hyperlynx we see that even a 3'' inch trace needs a series
termination to get a clean waveform at the receiver's end. We are using IBIS
models for the Xilinx Virtex FPGA and a Micron ZBT SRAM device.

-Arrigo

--
Dr. Arrigo Benedetti      o         e-mail: arrigo@vision.caltech.edu
Caltech, MS 136-93	 < >			phone: (626) 395-3695
Pasadena, CA 91125	 / \			fax:   (626) 795-8649

> > > At 09:21 AM 5/3/99 -0700, you wrote: > >Dear all, > > > >I would like to know you opinion on this issue. I am interfacing a > >state of the art FPGA with a high speed synchronous SRAM device. Since > >the interface is bidirectional (the FPGA will read and write data to > >the memory) I was wondering what is is the best way to terminate this > >bus. My intuition is that if the data lines are not very long, then a > >series termination near the FPGA end could have an effect similar to a > >series termination near the memory end when the memory is driving the > >bus. > > > >I've in the the standard SI book, and haven't found any hint on the > >problem. > > > >thanks in advance > > > >-Arrigo Benedetti > >-- > >Dr. Arrigo Benedetti e-mail: arrigo@vision.caltech.edu > >Caltech, MS 136-93 phone: (626) 395-3695 > >Pasadena, CA 91125 fax: (626) 795-8649 > > > >**** To unsubscribe from si-list: send e-mail to > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > si-list, for more help, put HELP. si-list archives are accessible at > http://www.qsl.net/wb6tpu/si-list **** > > > > > > **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

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