Ripple Measurements
The following table includes the ripple levels we measured on EDF550AWN’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 | 22.3mV | 14.2mV | 14.0mV | 12.6mV | Pass |
20% Load | 25.0mV | 14.5mV | 14.4mV | 13.1mV | Pass |
30% Load | 24.9mV | 14.9mV | 13.9mV | 14.1mV | Pass |
40% Load | 23.6mV | 14.8mV | 14.7mV | 15.2mV | Pass |
50% Load | 24.8mV | 15.8mV | 15.5mV | 15.6mV | Pass |
60% Load | 26.9mV | 16.0mV | 16.1mV | 15.9mV | Pass |
70% Load | 29.6mV | 17.3mV | 16.5mV | 17.0mV | Pass |
80% Load | 32.6mV | 18.1mV | 17.0mV | 17.9mV | Pass |
90% Load | 31.2mV | 18.4mV | 18.0mV | 16.5mV | Pass |
100% Load | 32.3mV | 18.7mV | 18.4mV | 19.2mV | Pass |
110% Load | 33.5mV | 18.9mV | 19.2mV | 19.6mV | Pass |
Crossload 1 | 40.4mV | 19.4mV | 19.2mV | 21.8mV | Pass |
Crossload 2 | 19.4mV | 15.4mV | 14.2mV | 23.8mV | Pass |
Ripple suppression was very good on all rails, which was not a surprise to us given the high-quality filtering capacitors that Enermax used in this unit's platform.
Ripple
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 0.01V/Div (each vertical division/box equals 0.01V) as the standard for all measurements.