cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 159

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

Revision 0.8
4.17 POWER MANAGEMENT CONTROL
The Power Management Control (PMC) module is a
GeodeLink Device whose function is to control all aspects
of power management. Power management is event driven
meaning that, in general, any action that the PMC performs
is predicated on some event. These events can come from
other GeodeLink Devices, including the CPU module inside
the GX2 for example, or events coming from other off-chip
sources.
The PMC is compatible with the industry standard power
management capabilities as defined in the Advanced Con-
figuration and Power Interface (ACPI) v2.0 specification. An
OS that conforms to ACPI can take advantage of the
CS5535 ACPI support hardware.
Advanced Power Management (APM) is another power
management approach that the PMC supports. APM is a
subset of ACPI and therefore will not be directly discussed.
Components in a GeodeLink architecture based system
have hardware and software means of performing power
management which the PMC controls. A high performance
computing system consumes multiple watts of power when
fully on. However, with GeodeLink architecture, system
power consumption is significantly lower on average
through the use of power states that reduce power needs
when the system is idle.
4.17.1 Power Domains
The PMC module consists of three blocks: Working
Standby and RTC.
G0: Working
G1: Idle
G2: Soft Off
G3: Mechanical Off
Global System
State
ACPI States
S3: Save-to-RAM
S4: Save-to-Disk
Table 4-34. Supported ACPI Power Management States
S1: Sleeping
Sleep State
Off
S0
S5
C State
Off
Off
Off
Off
C0
C1
C2
159
Suspend on
GX2 State
• The Working block contains all circuits and functions
• The Standby block contains all circuits and functions
• The RTC block contains the timing circuits for keeping
4.17.2 Power States
Table 4-34 shows the supported ACPI power states and
how they relate to the CS55335/GX2. ACPI power states
not described are not supported.
AHCG
Sleep
Halt
associated with the Working power domain. It includes
the Working state machine, Local bus interface, ACPI
power management registers, and power management
supporting logic (i.e., counters, timer, CCU, etc.). The
main function of the Working block is to put the system
into Sleep, that is, turn off clocks to the system and
disable I/Os to reduce power consumption.
associated with the Standby power domain. It includes
the Standby state machine, ACPI registers, and power
management supporting logic (i.e., counters, reset,
CCU, etc.). The function of the Standby logic is to
control power to the Working power domain. The PMC
disables all interfaces between the Standby and Working
domains while the Working power is off.
real time. These circuits are powered by V
It is not a device requirement that the RTC block be
powered during Mechanical Off. If a system design does
not require that real time be kept, then V
tied to ground.
FO
Off
Off
Off
Off
Working
CS5535
AHCG
AHCG
Logic
Sleep
Hardware States
FO
Off
Off
Off
Off
Auto-refresh
Auto-refresh
Memory
System
AHCG
AHCG
Main
FO
Off
Off
Off
BAT
BAT
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On (Sleep)
Standby
Standby
should be
CS5535
Standby
Logic
(ball A3).
On
Off