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Ripple Measurements

To learn how we measure ripple, please click here.

The following table includes the ripple levels we measured on the SFX L Power 600W's rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V and 5VSB).

Test	12V	5V	3.3V	5VSB	Pass/Fail
10% Load	8.1mV	8.0mV	11.9mV	6.0mV	Pass
20% Load	10.7mV	9.2mV	14.0mV	7.8mV	Pass
30% Load	13.7mV	11.0mV	17.7mV	8.8mV	Pass
40% Load	17.3mV	12.1mV	18.6mV	10.1mV	Pass
50% Load	22.0mV	14.6mV	19.6mV	11.7mV	Pass
60% Load	27.6mV	16.1mV	21.7mV	13.5mV	Pass
70% Load	30.3mV	17.8mV	25.5mV	15.3mV	Pass
80% Load	36.1mV	20.2mV	27.6mV	16.8mV	Pass
90% Load	40.0mV	21.4mV	30.1mV	19.2mV	Pass
100% Load	45.9mV	23.6mV	31.9mV	21.3mV	Pass
110% Load	57.4mV	25.2mV	35.8mV	23.8mV	Pass
Cross-Load 1	14.1mV	13.7mV	18.7mV	11.1mV	Pass
Cross-Load 2	52.8mV	21.9mV	30.2mV	18.8mV	Pass

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Ripple suppression on the +12V and 3.3V rails is average, while it's fairly good on the 5V and 5VSB rails. We would like to see below 40mV ripple at +12V under full load, and close to 25mV at 3.3V under the same conditions.

Ripple Oscilloscope Screenshots

The following oscilloscope screenshots illustrate the AC ripple and noise registered on the main rails (+12V, 5V, 3.3V and 5VSB). The bigger the fluctuations on the screen, the bigger the ripple/noise. We set 0.01 V/Div (each vertical division/box equals 0.01V) as the standard for all measurements.