Acoustics
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6 Acoustics
It is recommended that the power supply be designed with an appropriate fan,
internal impedance, and fan speed control circuitry capable of meeting the acoustic
targets listed in the below table.
The power supply assembly should not produce any prominent discrete tone
determined according to ISO 7779, Annex D.
Sound power determination is to be performed at 43° C, at 50% of the 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 43° C being derived
from the standard ambient assumption of 23° C, with 20 C added for the temperature
rise within the system (what is typically seen by the inlet fan). The declared sound
power shall be measured according to ISO 7779 and reported according to ISO 9296.
Different customers might have different acoustic specifications. Any power supply
design is recommended to follow any specific customer requirements.
Table 6-1: Recommended Power Supply Acoustic Targets
Idle (BA) Typical (50% load) (BA) Maximum (BA)
Minimum 3.5 4.0 5.0
Target 3.0 3.8 4.5
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