Gmch Core Voltage Plane And Decoupling; Power And Sleep State Definitions - Intel 855GME Design Manual

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Intel 855GME Chipset and Intel
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Table 22. Intel Pentium
Low-Frequency Decoupling (Polymer-Covered
Tantalum – POSCAP, Neocap, KO Cap)
High-Frequency Decoupling (0603 MLCC, >= X7R)
Place next to the CPU
4.4.5

GMCH Core Voltage Plane and Decoupling

The VCC-GMCH (1.35 V) plane feeds the internal core logic of the 82855GME. VCC-GMCH
does not employ on-package decoupling. To ensure accurate VCC-GMCH voltage on the GMCH
die, follow the decoupling guidelines listed in
layout style, and decoupling capacitor values must be used with no deviation.
4.5

Power and Sleep State Definitions

Suspend-To-RAM (STR): In the STR state, the system state is stored in main memory and all
Full-power operation:
Suspend operation:
Power rails:
Core power rail:
Standby power rail:
Derived power rail:
Dual power rail:
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6300ESB ICH Embedded Platform Design Guide
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M/Celeron M Processor V
Description
unnecessary system logic is turned off. Only main memory and logic
required to wake the system remain powered.
During full-power operation, all components on the motherboard remain
powered. Full-power operation includes both the full-on operating state
and the S1 (PROCESSOR stop-grant state) state.
During suspend operation; power is removed from some components on
the motherboard. The customer reference board supports three suspend
states: Suspend-to-RAM (S3), Suspend-to- Disk (S4), and Soft-off (S5).
An ATX power supply has 6 power rails: +5 V, -5 V, +12 V, -12 V,
+3.3 V, 5 Vsb. In addition to these power rails, several other power rails
are created with voltage regulators.
Power rail that is only on during full-power operation. These power rails
are on when the PSON signal is asserted to the ATX power supply. The
core power rails that are distributed directly from the ATX 12 V power
supply are +5 V, -5 V, +12 V, -12 V, +3.3 V.
A power rail that is on during suspend operation (these rails are also on
during full-power operation). These rails are on at all times (when the
power supply is plugged into AC power). The only standby power rail
that is distributed directly from the ATX power supply is: 5 Vsb
(5 V Standby). There are other standby rails that are created with voltage
regulators on the motherboard.
A derived power rail is any power rail generated from another power rail
using an onboard voltage regulator. For example, 3.3 Vsb is usually
derived (on the motherboard) from 5 Vsb using a voltage regulator.
A dual power rail is derived from different rails at different times
(depending on the power state of the system). Usually, a dual power rail
is derived from a standby supply during suspend operation and derived
from a core supply during full-power operation.
Note: The voltage on a dual power rail may be misleading.
January 2007
Decoupling Guidelines
CCP
Cap ESR
42 m Ω (typ)/2
2 x 150 µF
16 m Ω (typ)/10
10 x 0.1 µF
Table 24 on page 108. The component form factors,
ESL Notes
2.5 nH/2
0.6 nH/10
101