W83877ATG Nuvoton Technology Corporation of America, W83877ATG Datasheet - Page 104

• Manufacturer Part Number: W83877ATG
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83877ATG

• Lead Free Status / RoHS Status: Supplier Unconfirmed

9. ACPI /LEGACY FEATURE AND AUTO POWER MANAGEMENT
9.1
W83877ATF/ATG supports both ACPI and legacy power management models. For the ACPI power
management, the SCI pin is dedicated to the SCI interrupt signal for the SCI interrupt handler; For
the legacy power management, the SMI pin is dedicated to the SMI interrupt signal for the SMI
interrupt handler.
Two register blocks are used for the ACPI/Legacy power management. They are the PM1 and GPE
register blocks. Their base addresses are held in the W83877ATF/ATG configuration registers CR33
and CR34 respectively. Configuration registers CR40 to CR45 are for the legacy power management.
The above configuration registers hold the interrupt event enable and status bits of the SMI interrupts.
Control over the routing of SCI and SMI interrupts to the output pins is also contained in the above
registers.
One 24-bit power management timer is also implemented. It provides an accurate time value used by
the system software to measure and profile system idleness.
9.2
W83877ATF/ATG also provides the auto power management function for each device within it. They
are the printer port, FDC, UART A, and UART B devices in W83877ATF/ATG respectively. Device idle
and trap status are provided to indicate the device's working/sleeping state. Device idle timer with
programmable initial value is provided for each device, which enters the powerdown state when the
powerdown conditions are met. Any access to certain registers and external event input will wake up
the devices. The global stand-by timer deals with the other logic part excluding the printer port, FDC,
UART A , and UART B devices. The global stand-by timer reloads and counts down as soon as the 4
devices enter the powerdown mode and W83877ATF/ATG enters the powerdown mode as soon as it
expires. Once any device is awakened, the global stand-by is also awakened. The initial count values
of the devices are held in the configuration registers CR35 to CR39.
ACPI/Legacy power management
Device(auto) power management
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W83877ATF/W83877ATG
Publication Release Date:November 2006
Version 1.0