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NVIDIA Confidential
Prepared and Provided Under NDA
July 2007
DA-03414-001_v01
Application Note
INTEL CPU_VTT_PWRGD
Rise Time Requirement
DA-03414-001_v01 ii
July 26, 2007 NVIDIA CONFIDENTIAL
Document Change History
Version Date Responsible Reason for Change
01 July 25, 2007 JL, DV ?Initial release
?br>DA-03414-001_v01 1
July 26, 2007 NVIDIA CONFIDENTIAL
CPU_VTT_PWRGD Rise Time
Introduction
This application note discusses the required rise time for the CPU_VTT_PWRGD signal
to maintain compatibility with Intel CPUs. NVIDIA has found that some Intel
processors such as the Cedarmill, Presler, and Smithfield are sensitive to the risetime
of CPU_VTT_PWRGD, and may not boot properly if this time exceeds Intel抯
specification. NVIDIA recommends that all NVIDIA Intel based platforms must
meet this rise-time requirement. This includes NVIDIA C19, C55, MCP73, and
future Intel-based NVDIA SPP and MCP.
Work Around
The timing requirements should be satisfied by following Intel抯 Voltage Regulator-
Down (VRD) Design Guide for Desktop LGA775 Socket (Intel Document Number:
302356-004), version 10.1 or newer. The CPU_VTT_PWRGD rise time requirement
specified by Intel is less than 150 ns.
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?2007 NVIDIA Corporation. All rights reserved.
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