ATX Version 3.0 Multi Rail Desktop Platform Power Supply

Design Guide

ID 336521
Date 01/02/2022
Version 2.0
Public
Document Table of Contents

Output Ripple Noise - REQUIRED

The output ripple and noise requirements listed in Table 4-6 shall be met throughout the load ranges specified for the appropriate form factor and under all input voltage conditions as specified in Table 4-1.

Ripple and noise are defined as periodic or random signals over a frequency band of 10 Hz to 20 MHz. Measurements shall be made with an oscilloscope with 20 MHz of bandwidth. Outputs should be bypassed at the connector with a 0.1μF ceramic disk capacitor and a 10 μF electrolytic capacitor to simulate system loading. Refer to Figure 4-1 for the differential noise measurement setup.

Table 4-6: DC Output Noise/Ripple

Output

Maximum Ripple and Noise (mV p-p)

+12V1DC

120

+12V2DC

120

+5VDC

50

+3.3VDC

50

-12VDC

120

+5VSB

50

Figure 4-1: Differential Noise Test Setup

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