Intel ATX Power Supply Design Guide

Version 0.9

3.1.5 Catastrophic Failure Protection

The primary circuit design and the components specified in the same should be such that, should a component failure occur, the power supply should not exhibit any of the following:

∙Flame

∙Excessive smoke

∙Charred PCB

∙Fused PCB conductor

∙Startling noise.

3.2DC Output Requirements

3.2.1 DC Voltage Regulation

The DC output voltages shall remain within the regulation ranges shown in Table 3 when measured at the load end of the output connectors under all line, load, and environmental conditions. The voltage regulation limits shall be maintained under continuous operation for a period of time equal to or greater than the MTBF specified in Section 7.2 at any steady state temperature and operating conditions specified in Section 5.

Table 3: DC Output Voltage Regulation

Output

Range

Min.

Nom.

Max.

Unit

 

 

 

 

 

 

+12VDC*

±5%

+11.40

+12.00

+12.60

Volts

 

 

 

 

 

 

+5VDC

±5%

+4.75

+5.00

+5.25

Volts

 

 

 

 

 

 

+3.3VDC

±5%

+3.14

+3.30

+3.47

Volts

 

 

 

 

 

 

-5VDC

±10%

-4.50

-5.00

-5.50

Volts

 

 

 

 

 

 

-12VDC

±10%

-10.80

-12.00

-13.20

Volts

 

 

 

 

 

 

+5VSB

±5%

+4.75

+5.00

+5.25

Volts

*At +12 V peak loading, regulation at the +12VDC output can go to ±10%.

3.2.2Remote Sensing

The +3.3VDC output should have provisions for remote sensing to compensate for 100 mV of cable, connector, and PCB trace drops. The default sense should be connected to pin 11 of the ATX main power connector. The power supply should draw no more than 10 mA through the remote sense line to keep DC offset voltages to a minimum.

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