Intel SC5400LX User Manual

PWOK is a power OK signal and is pulled HIGH by the power supply to indicate all the outputs 
are within the regulation limits of the power supply. When any output voltage falls below 
regulation limits or when AC power has been removed for a time sufficiently long so that power 
supply operation is no longer guaranteed, PWOK is de-asserted to a LOW state. 

The purpose of the PSKill pin is to allow for hot swapping of the power supply. The PSKill pin on 
the power supply is shorter than the other signal pins. When a power supply is operating in 
parallel with other power supplies and then extracted from the system, the PSKill pin will quickly 
turn off the power supply and prevent arching of the DC output contacts. 

The power supply shall have a minimum MTBF at continuous operation of 100,000 hours at 
75% load and 30

  C, as calculated by Bellcore RPP, or 250,000 hours demonstrated at 75% 

load and 30

  C.  

In the redundant (1+1) parallel configuration (two power supply modules installed) the +12V 
output shared output current is enough current to meet voltage regulation limits during hot 
swapping and power supply failures. Hot swapping a power supply is the process of inserting 
and extracting a power supply from an operating power system while the AC cord is unplugged. 
During this process, the output voltages shall remain within the limits specified. In general, a 
failed supply may be removed and replaced with a good power supply. Hot swap works with 
operational as well as failed power supplies. There is a mechanical latch on the power supply to 
prevent the removal or insertion of a power supply while the AC power cord is plugged into the 
power supply. 

The power distribution board (PDB) is designed to plug directly to the output connector of the 
power supplies and contains the DC/DC power converters required to produce the output 
voltages: +3.3 VDC, +5 VDC and –12 VDC along with additional protection circuitry and a FRU 
EEPROM.