Intel SC5299WS User Manual

2.2.5.3 

Over-temperature Protection (OTP) 

The power supply is protected against over-temperature conditions caused by loss of fan 
cooling or excessive ambient temperature. In an OTP condition the power supply unit will shut 
down. When the power supply temperature drops to within specified limits, the power supply will 
restore power automatically, while the 5VSB remains always on. The OTP circuit must have 
built-in hysteresis such that the power supply will not oscillate on and off due to a temperature 
recovering condition. The OTP trip level has a minimum of 4

  C of ambient temperature 

hysteresis.  

2.2.6 

Control and Indicator Functions 

The following sections define the input and output signals from the power supply. Signals that 
can be defined as low true use the following convention:   

signal# = low true 

2.2.6.1 

PSON# Input Signal 

The PSON

#

 signal is required to remotely turn on/off the power supply. PSON

#

 is an active low 

signal that turns on the +3.3V, +5V, +12V, and -12V power rails. When this signal is not pulled 
low by the system, or left open, the outputs (except the +5VSB) turn off. This signal is pulled to 
a standby voltage by a pull-up resistor internal to the power supply. 

Signal Type

Accepts an open collector/drain input from the system. 
Pull-up to 5V located in power supply. 

PSON

#

 = Low  

ON 

PSON

#

 = High or Open 

OFF 

 

MIN 

MAX 

Logic level low (power supply ON) 

0V 

1.0V 

Logic level high (power supply OFF) 

2.0V 

5.25V 

Source current, Vpson = low 

 

4mA 

Power up delay: T

pson_on_delay

 5msec 

400msec 

PWOK delay: T 

pson_pwok

  

50msec 

2.2.6.2 

PWOK (Power OK) Output Signal 

PWOK is a power OK signal and is pulled HIGH by the power supply to indicate that 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 will be de-asserted to a LOW state. The start 
of the PWOK delay time is inhibited as long as any power supply output is in current limit.