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SSI
EPS2U Power Supply Design Guide, V2.1
3 Definitions/Terms/Acronyms
Required
The status given to items within this design guide, which are required to
meet SSI guidelines and a large majority of system applications.
Recommended
The status given to items within this design guide which are not required to
meet SSI guidelines, however, are required by many system applications.
Optional
The status given to items within this design guide, which are not required to
meet SSI guidelines, however, some system applications may optionally
use these features.
Autoranging
A power supply that automatically senses and adjusts itself to the proper
input voltage range (110 VAC or 220 VAC). No manual switches or
manual adjustments are needed.
CFM
Cubic Feet per Minute (airflow).
Dropout
A condition that allows the line voltage input to the power supply to drop to
below the minimum operating voltage.
Latch Off
A power supply, after detecting a fault condition, shuts itself off. Even if the
fault condition disappears, the supply does not restart unless manual or
electronic intervention occurs. Manual intervention commonly includes
briefly removing and then reconnecting the supply, or it could be done
through a switch. Electronic intervention could be done by electronic
signals in the Server System.
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.
Overcurrent
A condition in which a supply attempts to provide more output current than
the amount for which it is rated. This commonly occurs if there is a "short
circuit" condition in the load attached to the supply.
PFC
Power Factor Corrected.
Ripple
The periodic or random signals over a frequency band of 0 Hz to 20 MHz.
Rise Time
Rise time is defined as the time it takes any output voltage to rise from
10% to 95% of its nominal voltage.
Sag
The condition where the AC line voltage drops below the nominal voltage
conditions.
Surge
The condition where the AC line voltage rises above nominal voltage.
VSB or Standby Voltage
An output voltage that is present whenever AC power is applied to the AC
inputs of the supply.
MTBF
Mean time between failure.
PWOK
A typical logic level output signal provided by the supply that signals the
Server System that all DC output voltages are within their specified range.
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