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ATX12V Power Supply Design Guide
Version 2.0
7
1.2.3. Main Power Connector:
The 2 x 10 main power connector has been replaced by a 2 x 12 connector. This was made to
support 75 watt PCI Express*requirements. Pinout assignments are based on the SSI
recommendation.
With the added 12V, 5V, and 3.3V pins the need for an Aux Power connector is no longer
needed and the guidance for this connector has been removed.
1.2.4. Separate current limit for 12V2 on the 2x2 connector:
The 12V rail on the 2 x 2 power connector should be a separate current limited output to meet
the requirements of UL and EN 60950.
1.3 Terminology
The following terms are used in this document:
Term Description
Required
The status given to items within this design guide, which are required to meet
design guide and a large majority of system applications.
Recommended
The status given to items within this design guide, which are not required to
meet design guide, however, are required by many system applications.
Optional
The status given to items within this design guide, which are not required to
meet design guide, however, some system applications may optionally use these
features.
BA
Declared sound power, LwAd. The declared sound power level shall be
measured according to ISO* 7779 for the power supply and reported according
to ISO 9296.
CFM
Cubic Feet per Minute (airflow).
Monotonically
A waveform changes from one level to another in a steady fashion, without
intermediate retracement or oscillation.
Noise
The periodic or random signals over frequency band of 0 Hz to 20 MHz.