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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 PE-750's rails. The limits, according to the ATX specification, are 120 mV (+12V) and 50 mV (5V, 3.3V and 5VSB).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 26.4 mV | 7.5 mV | 18.9 mV | 6.0 mV | Pass |
| 20% Load | 13.5 mV | 8.9 mV | 19.6 mV | 8.1 mV | Pass |
| 30% Load | 15.7 mV | 9.7 mV | 22.0 mV | 9.4 mV | Pass |
| 40% Load | 16.7 mV | 11.3 mV | 24.0 mV | 11.5 mV | Pass |
| 50% Load | 19.2 mV | 13.7 mV | 27.2 mV | 13.7 mV | Pass |
| 60% Load | 22.6 mV | 15.8 mV | 29.2 mV | 15.4 mV | Pass |
| 70% Load | 24.4 mV | 17.5 mV | 30.8 mV | 18.0 mV | Pass |
| 80% Load | 27.1 mV | 19.0 mV | 32.1 mV | 19.3 mV | Pass |
| 90% Load | 29.0 mV | 21.1 mV | 33.8 mV | 21.1 mV | Pass |
| 100% Load | 31.8 mV | 24.0 mV | 37.2 mV | 23.9 mV | Pass |
| 110% Load | 35.3 mV | 27.4 mV | 48.3 mV | 27.6 mV | Pass |
| Cross-Load 1 | 21.0 mV | 8.9 mV | 20.9 mV | 6.1 mV | Pass |
| Cross-Load 2 | 31.7 mV | 23.4 mV | 36.6 mV | 23.1 mV | Pass |
Ripple suppression at +12V is very good, especially if we take into account this unit's SFX-L form factor, which doesn't allow the use of an increased number of filtering caps on the secondary side. Ripple is normal on the 5V and 5VSB rails, though it should be lower at 3.3V (less than 30 mV, worst-case).
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 0.01 V) as the standard for all measurements.
