Premio Computer Apollo/Shadowhawk - Manual (Page 104)

Technical Reference
81
2.11.3 Standby Current Requirements
CAUTION
If the standby current necessary to support multiple wake events from the PCI and/or USB buses
exceeds power supply capacity, the D845HV and D845WN boards may lose register settings stored
in memory, etc. Calculate the standby current requirements using the steps described below.
Power supplies used with the D845HV and D845WN boards must be able to provide enough
standby current to support the Instantly Available PC (ACPI S3 sleep state) configuration as
outlined in Table 51 below.
Values are determined by specifications such as PCI 2.2. Actual measured values may vary.
To estimate the amount of standby current required for a particular system configuration, standby
current requirements of all installed components must be added to determine the total standby
current requirement. Refer to the descriptions in Table 51 and review the following steps.
1. Note the total D845HV or D845WN board standby current requirement.
2. Add to that the total PS/2 port standby current requirement if a wake-enabled device is
connected.
3. Add, from the PCI 2.2 slots (wake enabled) row, the total number of wake-enabled devices
installed (PCI and AGP) and multiply by the standby current requirement.
4. Add, from the PCI 2.2 slots (nonwake enabled) row, the total number of wake-enabled devices
installed (PCI and AGP) and multiply by the standby current requirement.
5. Add all additional wake-enabled devices’ and nonwake-enabled devices’ standby current
requirements as applicable.
6. Add all the required current totals from steps 1 through 5 to determine the total estimated
standby current power supply requirement.
Table 51. Standby Current Requirements
Description
Standby Current
Requirements (mA) Instantly Available PC Current
Support (Estimated for
Integrated Board Components)
Total for D845HV board 394
PS/2 ports (Note) 345
PCI 2.2 slots (wake enabled) 375
PCI 2.2 slots (nonwake enabled) 20
CNR (Note) 375
Instantly Available PC Stand-by
Current Support
• Estimated for add-on
components
• Add to Instantly Available
PC total current
requirement
(See instructions above)
USB ports (Note) 500
Note: Dependent upon system configuration