[SI-LIST] Re: DDR1 without VTT termination
- From: "Kathiresan K" <k.kathir@xxxxxxxxx>
- To: "Ravinder.Ajmani@xxxxxxxxxxxxxx" <Ravinder.Ajmani@xxxxxxxxxxxxxx>
- Date: Tue, 1 Apr 2008 18:46:06 +0530
Hi All,
Thank you for your inputs. I thought that i would get some comments before
going for the simulation. I'll do the simulation and get back if there is
any problem.
Thanks,
Kathir
On 3/31/08, Ravinder.Ajmani@xxxxxxxxxxxxxx <Ravinder.Ajmani@xxxxxxxxxxxxxx>
wrote:
>
>
> Hi Kathiresan,
>
> I have designed two designs with single 32-bit DDR1 (160 MHz and 200 MHz).
> It is possible to realize these designs without VTT termination, if the
> trace length is kept small (< 1.5"), and Half-strength drivers are used at
> the DRAM. I used series terminations on the DDR side only, as my ASIC
> drivers are well behaved. If your processor has impedance matched drivers
> and the trace length can be further minimized, then you may even be able to
> use the Weak drivers on the DRAM without using any terminations.
>
> The best way to find it out will be by running a simulation.
>
> Regards, Ravinder
> Server PCB Development
> Hitachi Global Storage Technologies
>
>
> Email: Ravinder.Ajmani@xxxxxxxxxxxxxx
>
>
> *"Kathiresan K" <k.kathir@xxxxxxxxx>*
> Sent by: si-list-bounce@xxxxxxxxxxxxx
>
> 03/31/2008 07:18 AM
> To
> si-list@xxxxxxxxxxxxx cc
> Subject
> [SI-LIST] DDR1 without VTT termination
>
>
>
>
> Hi,
> I need to have a single chip DDR1 (160 MHz, 16-Bit) memory for a
> processor.
> I don't want to provide VTT terminations. I'll keep the trace length as
> minimum as possible. I may provide series termination but I haven't done
> pre-layout simulation yet.
> Can somebody please clarify whether it can be designed without VTT
> termination? If yes, what can be the maximum trace length I go for? If I'm
> providing series termination, should I provide at both the ends for
> bi-directional signals?
>
> Regards,
> Kathir
>
>
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