Design Guide
161
Platform Power Delivery Guidelines
12.1.1
Processor Core Voltage
The processor core voltage power plane is used to power the processors. The processor core
voltage operates between 1.30 V and 1.50 V. A VRM 9.1 compatible design is required for all
Xeon platforms. The Voltage Regulator solution can be either a VRM 9.1 or a VRDown design.
Refer to the
Voltage Regulator Module (VRM) 9.1 DC-DC Converter Design Guidelines, Dual
Intel
®
Xeon™ Processor Voltage Regulator Down (VRD) Design Guidelines,
and
603 Pin Socket
Design Guidelines
for more information.
12.1.2
2.5 V
The 2.5 V power plane is used to provide power to the DDR DRAM core, the MCH DDR IO ring,
and reference voltage to the 1.25 V switching regulator. The 2.5 V power plane is created using a
switching regulator, which should be able to support up to 26 A of current. This switching regulator
receives its input directly from the 5 V power rail of the power supply. The DDR DRAM core
requires at most 20.0 A of current. This value is a worst-case current, and is based on DRAM
vendor specific specification for maximum current. Power levels will vary. In some cases, current
requirements may be less than half of this maximum value, but a maximum current level of 20 A
should be used to allow interoperability among DRAM devices. The current dedicated for VDD in
the MCH is 5.8 A. This regulator is required in all designs.
12.1.3
1.25 V
A voltage regulator derived off 2.5 V produces two 1.25 V rails. One is for the MCH reference
voltage (VREF); the other is for DDR termination voltage (VTERM). The switching regulator
divides the 2.5 V power rail by 2 to drive 1.25 V reference voltage. This provides some common
mode noise rejection between the DDR termination and I/O voltages. The entire power plane
requires about 12 A of maximum current, and can be achieved by using either one or two
regulators (one for both channels or one for each channel).
12.1.4
1.8 V
The 1.8 V power plane is created using a switching regulator sourcing from the 5 V power rail on
the power supply. The 1.8 V plane powers the ICH3-S core logic, the 1.2 V regulator, and the hub
interface I/O rings of the P64H2s. This voltage rail requires approximately 11.63 A maximum
current. The hub interface on each P64H2 device consumes about 2.66 A. The hub interface on the
ICH3-S device consumes about 550 mA of current. This regulator is required in all designs.
12.1.5
1.2 V
The 1.2 V power plane powers the MCH core logic. The MCH core logic requires 3.1 A. A
switching regulator using either the 3.3 V or the 5 V power rail is the regulator’s input to power the
1.2V plane.
12.1.6
5 VSB
The 5 VSB power plane comes directly off the 5 VSB power rail and has two functions, to provide
power to resume functions via a 3.3 VSB regulator in I/O devices off of the ICH3-S, and to provide
1.8 VSB power through a linear regulator. The resume I/O segment of the ICH3-S requires 64 mA
of current, while the 5 VSB-to-1.8 VSB regulator requires 14.01 mA.
Summary of Contents for Xeon
Page 24: ...Introduction 24 Design Guide This page is intentionally left blank ...
Page 30: ...Component Quadrant Layout 30 Design Guide This page is intentionally left blank ...
Page 52: ...Platform Clock Routing Guidelines 52 Design Guide This page is intentionally left blank ...
Page 66: ...System Bus Routing Guidelines 66 Design Guide This page is intentionally left blank ...
Page 118: ...Intel 82870P2 P64H2 118 Design Guide This page is intentionally left blank ...
Page 146: ...I O Controller Hub 146 Design Guide This page is intentionally left blank ...
Page 148: ...Debug Port 148 Design Guide This page is intentionally left blank ...
Page 210: ...Schematic Checklist 210 Design Guide This page is intentionally left blank ...
Page 220: ...Layout Checklist 220 Design Guide This page is intentionally left blank ...
Page 222: ...Schematics 222 Design Guide This page is intentionally left blank ...