Standby Current Requirements - Intel D845EPT2 Specification

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 Desktop Boards D845EBG2 and D845EPT2 may lose register
settings stored in memory, etc. Calculate the standby current requirements using the steps
described below.
Power supplies used with the Desktop Boards D845EBG2 and D845EPT2 must be able to provide
enough standby current to support the Instantly Available PC (ACPI S3 sleep state) configuration
as outlined in Table 50 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 50 and review the following steps.
1. Note the total Desktop Board D845EBG2 or D845EPT2 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 50.

Standby Current Requirements

Instantly Available PC Current
Support (Estimated for
Integrated Desktop Board
Components)
Instantly Available PC Stand-by
Current Support
•
Estimated for add-on
components
•
Add to Instantly Available
PC total current
requirement
(See instructions above)
Notes:
1. This total is based on a system configuration not including audio or LAN.
2. Dependent upon system configuration.
3. 40 mA for the Desktop Board D845EPT2.
100 mA for the Desktop Board D845EBG2.
Description
Total for Desktop Board
D845EBG2
(Note 2)
PS/2 ports
PCI 2.2 slots (wake enabled)
PCI 2.2 slots (nonwake enabled)
(Note 2)
CNR
(Note 2)
USB ports
Technical Reference
Standby Current
Requirements (mA)
(Note 1)
220 mA
345 mA
375 mA
(Note 3)
375 mA
500 mA
81