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July 17, 2002
35
Processor Power Supplies and Power
Management
3.2 Power Supply Sequencing
3.2.1 Power Sequencing Requirements
In order to prevent a high startup current condition on the processor I/O power supplies, it is required that the
processor core power supply (V_CPU_CORE) be turned on first and reach a level of V_CPU_CORE
MIN
or
greater, prior to applying the processor 2.5 V and 3.3 V I/O voltages (V2_5 and V3_3, respectively). After
V_CPU_CORE has reached V_CPU_CORE
MIN
or greater, V3_3 and V2_5 can be supplied to the processor
in any order.
A diagram of the power supply sequencing required for TM5500/TM5800 processors is shown in the figure
below. System designs for TM5500/TM5800 processors must also meet the power-on requirements specified
in the
Data Book
.
The table below provides timing specifications for the power supply sequencing figure above.
Note
See the
Data Book
for more information on power sequencing requirements for TM5500/TM5800
processors.
Figure 4:
Power Supply Sequencing
Table 10:
Power Supply Sequencing Timing Specifications
Timing
Value
Description
Min
Max
T1
Time from V_CPU_CORE valid to beginning ramp of V3_3 and V2_5
0 mS
50 mS
T2
Time from V_CPU_PLL valid to PCI_RST# deassertion
20 mS
-
T3
Time from V_CPU_CORE valid to PCI_RST# deassertion
20 mS
-
T4
Time from V3_3 and V2_5 valid to PCI_RST# deassertion
1 mS
-
V_CPU_PLL
V_CPU_CORE
V3_3 and V2_5
V_CPU_PLL valid
V_CPU_CORE valid
V3_3 and V2_5 valid
PCI_RST#
PCI_RST# deasserted
T2
T3
T1
T4
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...