ATX12V Power Supply Design Guide
Version 2.0 Final Review Copy
5.5. Mechanical Shock
50 g, trapezoidal input; velocity change ≥ 170 in/s | |
| Three drops on each of six faces are applied to each sample. |
5.6. Random Vibration
0.01 g²/Hz at 5 Hz, sloping to 0.02 g²/Hz at 20 Hz, and | |
| maintaining 0.02 g²/Hz from 20 Hz to 500 Hz. The area under |
| the PSD curve is 3.13 gRMS. The duration shall be 10 minutes |
| per axis for all three axes on all samples. |
5.7. Acoustics
For power supplies designed for low noise, the following provides some general guidance.
Guidelines Sound Power: The power supply assembly shall not produce a declared sound power level greater than 4.0 BA. Sound power determination is to be performed at 43C, 50% of maximum rated load, at sea level. This test point is chosen to represent the environment seen inside a typical system at the idle acoustic test condition, with the 43C being derived from the standard ambient assumption of 23C, with 20C added for the temperature rise within the system (what is typically seen by the inlet fan). The declared sound power level shall be measured according to ISO 7779 and reported according to ISO 9296.
Pure Tones: The power supply assembly shall not produce any prominent discrete tone determined according to ISO 7779, Annex D.
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