FreeLists / si-list / [SI-LIST] Re: return path

[scott@xxxxxxxxxxxxx]

Actually, there is one other reason.  The DDR2 modules are routed in the same 
way.  Keeping Address/Command signals referenced to VDD keeps the signal return 
path continuous across the DDR2 memory connector.

>----- ------- Original Message ------- -----
>From: weirsi@xxxxxxxxxx
>To: chrice102@xxxxxxxx
>Sent: Tue, 08 Apr 2008 03:33:59
>
>chrice102 yes that is the only reason.
>
>Steve
>
>chrice102 wrote:
>> hi steve
>> thank you for your replies! in our motherboard
>system,the layers is S
>> V G S.and we route the command and control
>signals on TOP layer.so we
>> have to split vcc plane into vdd and gnd in ddr
>area.the DQ signal ref
>> the gnd plane ,the command and control signal ref
>the vdd .you said
>> "Vdd reference on address / control supports low
>cost PCBs.".this is
>> the only reason?
>> 2008-04-08
>>
>---------------------------------------------------
>---------------------
>> chrice102
>>
>---------------------------------------------------
>---------------------
>> *发件人：* steve weir
>> *发送时间：* 2008-04-08 16:37:51
>> *收件人：* chrice102
>> *抄送：* si-list@xxxxxxxxxxxxx
>> *主题：* Re: [SI-LIST] return path
>> Vdd reference on address / control supports low
>cost PCBs.
>> ODT on common lines requires enabling in one chip
>only via control
>> registers. The address lines are used to access
>the control registers.
>> Steve.
>> chrice102 wrote:
>> > hi all
>> > I have some problems :In DDR system,the
>reference plane of ADDRS
>> signals is Vddr,why isn't gnd plane? and why does
>the chip vendor also
>> put the terminater of the ADDRS signal into the
>chip?
>> > 2008-04-08
>> >
>> >
>> >
>> > chrice102
>> >
>> >
>> >
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>> -- 
>> Steve Weir
>> Teraspeed Consulting Group LLC
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>-- 
>Steve Weir
>Teraspeed Consulting Group LLC 
>121 North River Drive 
>Narragansett, RI 02882 
>
>California office
>(866) 675-4630 Business
>(707) 780-1951 Fax
>
>Main office
>(401) 284-1827 Business 
>(401) 284-1840 Fax 
>
>Oregon office
>(503) 430-1065 Business
>(503) 430-1285 Fax
>
>http://www.teraspeed.com
>This e-mail contains proprietary and confidential
>intellectual property of Teraspeed Consulting Group
>LLC
>---------------------------------------------------
>---------------------------------------------------
>Teraspeed(R) is the registered service mark of
>Teraspeed Consulting Group LLC
>
>---------------------------------------------------
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