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July 17, 2002
44
Processor Power Supplies and Power
Management
ACPI Quick Start State (C2)
The C0 to C2 transition is caused by the assertion of the STPCLK# signal. The processor issues a Stop Grant
cycle in response to the STPCLK# assertion, then enters the C2 state. The C2 to C0 transition is caused by
the deassertion of the STPCLK# signal.
Refer to the above table for a description of the notes in the diagram below:
ACPI Deep Sleep State (C3)
The C0 to C3 transition is caused by an I/O cycle to the power management controller, followed by the
assertion of the STPCLK# signal, followed by the assertion of the SLEEP# signal, and then the shutdown of
the host clock. The C3 to C0 transition is accomplished by the opposite sequence of signals (restart
processor clock, deassert SLEEP#, deassert STPCLK#).
The I/O cycle that initiates the C3 power state is typically snooped by the processor. The processor integrated
northbridge must be properly configured to snoop this I/O cycle, and the power management software must
not use or employ any other means aside from this I/O cycle to trigger a state transition to C3. The power
management controller must allow the I/O cycle to complete before asserting STPCLK#.
State Transition
Timing Information/Requirements
Diagram Note
STPCLK# assertion to Stop Grant cycle
3.5 µS typical
8 µS maximum
T1
STPCLK# deassertion to C0
3
µ
S typical
5
µ
S maximum
T2
State Transition
Timing Information/Requirements
Diagram Note
STPCLK# assertion to Stop Grant cycle
3.5 µS typical
8 µS maximum
T1
Stop Grant to SLEEP# assertion latency
2 µS minimum
T2
SLEEP# hold time
100 nS minimum required
T3
SLEEP# assertion to host clock shutdown
17 nS minimum required
T4
Host clock restart to SLEEP# deassertion
20 µS minimum required
T5
Quick Start (C2)
CPU_CLK
STPCLK#
Stop Grant
x86
execution
T1
T2
Содержание Crusoe TM5500
Страница 1: ...TM5500 TM5800 System Design Guide July 17 2002...
Страница 6: ...July 17 2002 6 List of Tables...
Страница 8: ...July 17 2002 8 List of Figures...
Страница 50: ...July 17 2002 50 Processor Power Supplies and Power Management...
Страница 110: ...July 17 2002 110 System Design Considerations...
Страница 122: ...July 17 2002 122 System Design Checklists...
Страница 128: ...July 17 2002 128 Serial Write protection PLD Data...
Страница 130: ...July 17 2002 130 Index...