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Ripple Measurements
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The following table includes the ripple levels we measured on the BF450G’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 | 13.5mV | 7.0mV | 6.2mV | 9.2mV | Pass |
| 20% Load | 22.4mV | 6.1mV | 5.9mV | 9.1mV | Pass |
| 30% Load | 24.7mV | 6.6mV | 6.3mV | 10.5mV | Pass |
| 40% Load | 22.5mV | 6.7mV | 7.0mV | 10.7mV | Pass |
| 50% Load | 21.9mV | 7.8mV | 7.4mV | 11.0mV | Pass |
| 60% Load | 24.3mV | 8.8mV | 8.3mV | 11.6mV | Pass |
| 70% Load | 26.3mV | 10.5mV | 10.3mV | 12.1mV | Pass |
| 80% Load | 25.7mV | 14.3mV | 15.3mV | 18.5mV | Pass |
| 90% Load | 26.3mV | 16.8mV | 18.8mV | 19.5mV | Pass |
| 100% Load | 29.0mV | 13.9mV | 15.2mV | 21.7mV | Pass |
| 110% Load | 27.7mV | 13.9mV | 14.3mV | 25.1mV | Pass |
| Cross-Load 1 | 28.0mV | 12.6mV | 11.5mV | 6.4mV | Pass |
| Cross-Load 2 | 24.5mV | 10.3mV | 13.5mV | 11.5mV | Pass |
Ripple suppression was very good on every rail. And strangely enough, the ripple at +12V with 110% load decreased slightly; normally we'd expect the opposite. The 3.3V rail also behaves strangely, registering its peak ripple reading with 90% load.
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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