Intel ATX Power Supply Design Guide

Version 0.9

3. Electrical Specification

The electrical requirements that follow are to be met over the environmental ranges specified in Section 5 unless otherwise noted.

3.1 AC Input Requirements

The power supply shall be capable of supplying full rated output power over two input voltage ranges rated 100-127 VAC and 200-240 VAC RMS nominal. The correct input range for use in a given environment may be either switch-selectable or auto-ranging. The power supply shall automatically recover from AC power loss. The input voltage, current, and frequency requirements for continuous operation are stated below. (Note that nominal voltages for test purposes are considered to be within ±1.0 V of nominal.) The power supply must be able to start up under peak loading at 90 VAC.

Table 1: AC Input Line Requirements

Parameter

Min

Nom

Max

Unit

 

 

 

 

 

Vin (115 VAC)

90

115

135

VACrms

Vin (230 VAC)

180

230

265

VACrms

Vin Frequency

47

--

63

Hz

 

 

 

 

 

 

Iin

(115 VAC)

 

 

7.0

Arms

 

 

 

 

 

 

Iin

(230 VAC)

 

 

3.5

Arms

 

 

 

 

 

 

3.1.1 Input Overcurrent Protection

The power supply shall incorporate primary fusing for input overcurrent protection. Fuses should be slow-blow type or equivalent to prevent nuisance trips.

3.1.2 Inrush Current Limiting

Maximum inrush current from power-on (with power on at any point on the AC Sine) and including, but not limited to, three line cycles, shall be limited to a level below the surge rating of the input line cord, AC switch if present, bridge rectifier, fuse, and EMI filter components. Repetitive ON/OFF cycling of the AC input voltage should not damage the power supply or cause the input fuse to blow.

3.1.3 Input Undervoltage

The power supply shall contain protection circuitry such that the application of an input voltage below the minimum specified in Section 3.1, Table 1, shall not cause damage to the power supply.

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