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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 650 GM’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 | 12.5mV | 8.9mV | 9.8mV | 4.4mV | Pass |
| 20% Load | 13.3mV | 9.2mV | 10.2mV | 4.9mV | Pass |
| 30% Load | 15.6mV | 10.5mV | 11.0mV | 6.3mV | Pass |
| 40% Load | 19.2mV | 12.1mV | 11.9mV | 7.7mV | Pass |
| 50% Load | 22.6mV | 14.1mV | 13.8mV | 9.1mV | Pass |
| 60% Load | 26.2mV | 16.6mV | 15.4mV | 10.8mV | Pass |
| 70% Load | 30.5mV | 18.8mV | 17.3mV | 12.6mV | Pass |
| 80% Load | 34.0mV | 21.0mV | 19.3mV | 14.2mV | Pass |
| 90% Load | 37.9mV | 23.3mV | 21.8mV | 15.3mV | Pass |
| 100% Load | 41.0mV | 25.4mV | 23.0mV | 17.1mV | Pass |
| 110% Load | 45.2mV | 27.4mV | 24.9mV | 18.8mV | Pass |
| Cross-Load 1 | 15.6mV | 12.0mV | 14.9mV | 5.4mV | Pass |
| Cross-Load 2 | 40.9mV | 23.2mV | 20.7mV | 15.3mV | Pass |
The ripple suppression we observe is not up to today's high-end standards. It's good enough, though, especially when we take into account that this is an SFX-based power supply. Still, it'd be nice to see close to 30mV ripple at +12V and below 20mV on the minor rails under full 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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