Ripple Measurements
In the following table you will find the ripple levels that we measured on the main rails of SPCR2-850P. According to ATX specification the limits are 120 mV (+12V) and 50 mV (5V & 3.3V).
Ripple Measurements |
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Test | 12 V | 5 V | 3.3 V | Pass/Fail |
20% Load | 53.4 mV | 11.2 mV | 13.2 mV | Pass |
40% Load | 62.4 mV | 12.6 mV | 15.8 mV | Pass |
50% Load | 68.8 mV | 13.8 mV | 17.2 mV | Pass |
60% Load | 75.2 mV | 14.2 mV | 17.6 mV | Pass |
80% Load | 87.8 mV | 15.6 mV | 19.8 mV | Pass |
100% Load | 99.6 mV | 15.8 mV | 20.8 mV | Pass |
Crossload 1 | 72.4 mV | 22.8 mV | 23.2 mV | Pass |
Crossload 2 | 97.8 mV | 11.2 mV | 16.8 mV | Pass |
Ripple suppression on the minor rails is quite good but at +12V is lousy. In a modern PSU we expect ripple at +12V to not go beyond 70-80mV in all cases, but here it reached 100mV. Sirtec has to focus more on ripple/noise suppression with their implementations, since the competition is years ahead at this field.
Ripple at Full Load
In the following oscilloscope screenshots you can see the AC ripple and noise that the main rails registered (+12V, 5V, 3.3V). The bigger the fluctuations on the oscilloscope's screen the bigger the ripple/noise. We usually set 0.01 V/Div (each vertical division/box equals to 0.01V) as standard but at this case we were forced to use 0.02 V/Div at all screenshots, since ripple was very high at +12V.
Ripple at Crossload 1
The order of images is +12V, 5V and 3.3V.
Ripple at Crossload 2
As above the order of images is +12V, 5V and 3.3V.