ACC2087 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

ACC2087

ENHANCED SUPER CHIP

Unspecified 

ACC MicroTM

2087

2.9 Power Management Features

The ACC2087 provides a powerful mechanism of system power management that is completely transparent to

the operating system and application software. It was designed from the system level to synthesize and manage

power consumption for the lowest power operation while maintaining system performance in the portable

system.

The ACC2087 implements four special power saving modes to provide the most sophisticated system

information needed for power management application. They are "Local Standby" , "Global Standby" ,

"Suspend / Resume" , and "Doze" mode. The ACC2087 also provides a dedicated battery low input pin

(LBAT#) and warning timer for an external battery pack. A transition on LBAT# should trigger this

programmed warning timer. A 1khz tone will be generated through the speaker output as soon as the LBAT#

transition is detected. If no transition has been detected, upon warning timer time-out, an SMI will be

generated.

Local Standby Mode (LSM)

The "Local Standby" mode provides three dedicated local standby control circuits to monitor activity on HDD ,

I/O address for general chip select (GCS), and VRAM, Keyboard/Mouse, respectively. When the associated

programmed timer is timed out, an optional SMI will be generated and status bit will be set. Any break event

such as hard disk access will generate SMI and bring system back to normal operation.

Global Standby Mode (GSM)

When the system has been idle for a programmed standby timer count , and there is

no screen activity for a programmed VRAM count, the system can go into global standby mode. All of the

peripheral devices can be powered off and the CPU clock can be stopped under global standby mode.

Suspend and Resume Mode

The suspend mode can be entered by pressing the suspend/resume button or receiving a low battery input. In

addition to the suspend / resume button, the ACC2087 has two user-defined buttons, User button and Standby

button, which can bring the system to suspend mode.

The suspend to disk and resume feature is also supported by the ACC2087 through the SL-compatible shadow

register.

Doze Mode

Doze mode provides a mechanism that allows power saving even between the keystrokes. This mechanism

utilizes the Frequency Modulation (FM) and Pulse Modulation (PM) techniques which are commonly used in

the

telecommunications field. This mode is used not only to provide the temperature control when CPU is busy

(non-Doze) but also to further reduce power consumption when CPU is not busy (Doze).

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