82801BA Datasheet, PDF (76/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

Functional Description
Power States
The LAN Controller contains power management registers for PCI and implements all four power
states defined in the Power Management Network Device Class Reference Specification, Rev. 1.0.
The four states, D0 through D3, vary from maximum power consumption at D0 to the minimum
power consumption at D3. PCI transactions are only allowed in the D0 state, except for host
accesses to the LAN Controller’s PCI configuration registers. The D1 and D2 power management
states enable intermediate power savings while providing the system wake-up capabilities. In the
D3 state, the LAN Controller can provide wake-up capabilities. Wake-up indications from the LAN
Controller are provided by the Power Management Event (PME#) signal.
• D0 Power State. As defined in the Network Device Class Reference Specification, the device
is fully functional in the D0 power state. In this state, the LAN Controller receives full power
and should be providing full functionality. In the LAN Controller the D0 state is partitioned
into two substates, D0 Uninitialized (D0u) and D0 Active (D0a).
D0u is the LAN Controller’s initial power state following a PCI RST#. While in the D0u state,
the LAN Controller has PCI slave functionality to support its initialization by the host and
supports Wake on LAN* mode. Initialization of the CSR, Memory, or I/O Base Address
Registers (PCI Configuration space) switches the LAN Controller from D0u state to D0a state.
In the D0a state, the LAN Controller provides its full functionality and consumes its nominal
power. In addition, the LAN Controller supports wake on link status change (see
Section 5.2.3.3). While it is active, the LAN Controller requires a nominal PCI clock signal (in
other words, a clock frequency greater than 16 MHz) for proper operation. The LAN
Controller supports a dynamic standby mode. In this mode, the LAN Controller is able to save
almost as much power as it does in the static power-down states. The transition to or from
standby is done dynamically by the LAN Controller and is transparent to the software.
• D1 Power State. For a device to meet the D1 power state requirements, as specified in the
Advanced Configuration and Power Interface (ACPI) Specification, Revision 1.0, it must not
allow bus transmission or interrupts; however, bus reception is allowed. Therefore, device
context may be lost and the LAN Controller does not initiate any PCI activity. In this state, the
LAN Controller responds only to PCI accesses to its configuration space and system wake-up
events.
The LAN Controller retains link integrity and monitors the link for any wake-up events such
as wake-up packets or link status change. Following a wake-up event, the LAN Controller
asserts the PME# signal.
• D2 Power State. The ACPI D2 power state is similar in functionality to the D1 power state. In
addition to D1 functionality, the LAN Controller can provide a lower power mode with wake-
on-link status change capability. The LAN Controller may enter this mode if the link is down
while the LAN Controller is in the D2 state. In this state, the LAN Controller monitors the link
for a transition from an invalid to a valid link.
The sub-10 mA state due to an invalid link can be enabled or disabled by the PME_EN bit in
the Power Management Driver Register (PMDR). The LAN Controller will consume in D2
10 mA regardless of the link status. It is the LAN Connect component that consumes much
less power during link down, hence LAN Controller in this state can consume <10 mA.
• D3 Power State. In the D3 power state, the LAN Controller has the same capabilities and
consumes the same amount of power as it does in the D2 state. However, it enables the PCI
system to be in the B3 state. If the PCI system is in the B3 state (in other words, no PCI power
is present), the LAN Controller provides wake-up capabilities. If PME is disabled, the LAN
Controller does not provide wake-up capability or maintain link integrity. In this mode the
LAN Controller consumes its minimal power (if PME_EN=0).
The LAN Controller enables a system to be in a sub-5 watt state (low power state) and still be
virtually connected. More specifically, the LAN Controller supports full wake-up capabilities
while it is in the D3 cold state. The LAN Controller is in the ICH2 resume well and, thus, is
connected to an auxiliary power source (a separate LAN well). This enables it to provide
wake-up functionality while the PCI power is off.
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82801BA ICH2 and 82801BAM ICH2-M Datasheet