Technical Reference
51
2.5
Electrical Considerations
2.5.1
Power Supply Considerations
CAUTION
The +5 V standby line from the power supply must be capable of providing adequate
+5 V standby current. Failure to do so can damage the power supply. The total
amount of standby current required depends on the wake devices supported and
manufacturing options.
Additional power required will depend on configurations chosen by the integrator.
The power supply must comply with the indicated parameters of the ATX form factor
specification.
•
The potential relation between 3.3 VDC and +5 VDC power rails
•
The current capability of the +5 VSB line
•
All timing parameters
•
All voltage tolerances
For example, for a system consisting of a D945GCLF board (with integrated Intel Atom
processor at 4 W), 2 GB DDR2 RAM, one hard disk drive, one optical drive, and all
board peripherals enabled, the minimum recommended power supply is 75 W. Table
20 lists the recommended power supply current values.
Table 21. Recommended Power Supply Current Values
Output Voltage
3.3 V
5 V
12 V1
12 V2
-12 V
5 VSB
Current
0.51 A
7.75 A
0.52 A
0.32 A
0.018 A
0.3 A
2.5.2
Fan Header Current Capability
CAUTION
The processor fan must be connected to the processor fan header, not to a chassis fan
header. Connecting the processor fan to a chassis fan header may result in onboard
component damage that will halt fan operation.
Table 22 lists the current capability of the fan headers.
Table 22. Fan Header Current Capability
Fan Header
Maximum Available Current
GMCH fan
2.0 A
Rear chassis fan
1.5 A