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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 SF450’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 | 5.5mV | 6.8mV | 4.5mV | 7.6mV | Pass |
| 20% Load | 8.5mV | 7.2mV | 5.3mV | 9.2mV | Pass |
| 30% Load | 11.0mV | 7.6mV | 5.6mV | 9.0mV | Pass |
| 40% Load | 12.7mV | 7.9mV | 6.2mV | 8.6mV | Pass |
| 50% Load | 15.2mV | 8.7mV | 6.8mV | 8.7mV | Pass |
| 60% Load | 26.5mV | 9.4mV | 8.7mV | 11.3mV | Pass |
| 70% Load | 18.9mV | 10.2mV | 10.2mV | 10.2mV | Pass |
| 80% Load | 19.9mV | 11.0mV | 11.7mV | 11.2mV | Pass |
| 90% Load | 21.7mV | 11.3mV | 11.1mV | 12.5mV | Pass |
| 100% Load | 23.3mV | 12.0mV | 11.1mV | 13.6mV | Pass |
| 110% Load | 25.8mV | 12.1mV | 10.9mV | 14.7mV | Pass |
| Cross-Load 1 | 9.9mV | 11.6mV | 11.2mV | 15.6mV | Pass |
| Cross-Load 2 | 23.6mV | 8.1mV | 6.8mV | 15.0mV | Pass |
Ripple suppression is great on every rail, despite the lack of in-cable capacitors. Plenty of polymer caps on the secondary side, along with a few electrolytic ones, enable clean DC rails.
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.
Ripple At Full Load
Ripple At 110-Percent Load
Ripple At Cross-Load 1
Ripple At Cross-Load 2
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