January 2007
105
Intel
®
855GME Chipset and Intel
®
6300ESB ICH Embedded Platform Design Guide
4.7
Intel 855GME Chipset Platform Power-Up Sequence
The following sections describe the power-on timing sequence for Intel 855GME chipset Graphics
Memory Controller Hub (82855GME) based platforms.
4.7.1
GMCH Power Sequencing Requirements
All GMCH power rails shall be stable before PWROK is asserted. The power rails may be brought
up in any order desired
.
However, good design practice would have all GMCH power rails
come up as close in time as practical, with the core voltage (1.35 V) coming up first. RSTIN#,
which brings GMCH out of reset, shall be deasserted only after PWROK has been active for 1 ms.
After GMCH is out of reset, it deasserts CPURST# within 1 ms.
4.7.2
6300ESB Power Sequencing Requirements
4.7.2.1
V
5REF
/3.3V Sequencing
V5REF is the reference voltage for 5 V tolerance on inputs to the 6300ESB. V5REF must be
powered up before Vcc3_3, or after Vcc3_3 within 0.7 V. Also, V5REF must power down after
Vcc3_3, or before Vcc3_3 within 0.7 V. It must also power down after or simultaneous to Vcc3_3.
These rules must be followed to ensure the safety of the 6300ESB. If the rule is violated, internal
diodes will attempt to draw power sufficient to damage the diodes from the Vcc3_3 rail.
shows a sample implementation of how to satisfy the V5REF/3.3 V sequencing rule.
This rule also applies to V5REF_Sus and VccSus3_3. However, in most platforms, the VccSus3_3
rail is derived from the 5 VSB through a voltage regulator and therefore, the VccSus3_3 rail will
always come up after the VccSus5 rail. As a result, V5REF_Sus (which is derived directly from
Figure 49. GMCH Power-up Sequence
CPURST#
RSTIN#
1ms min
1ms max
PWROK
GMCH PWR
Rails
Содержание 6300ESB ICH
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Страница 36: ...36 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide General Design Considerations...
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Страница 152: ...152 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide System Memory Design Guidelines DDR SDRAM...
Страница 172: ...172 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide Integrated Graphics Display Port...
Страница 190: ...190 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide Hub Interface...
Страница 246: ...246 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide Intel 6300ESB Design Guidelines...
Страница 264: ...264 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide Platform Clock Routing Guidelines...
Страница 298: ...298 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide Schematic Checklist Summary...
Страница 318: ...318 Intel 855GME Chipset and Intel 6300ESB ICH Embedded Platform Design Guide Layout Checklist...