Sun Microsystems Sun Blade 100, Service Manual

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C-12 Sun Blade 100 Service Manual • October 2000
When the system is off, the switch will turn the power supply on. When the system
is already on, the button will send an interrupt to the system software. The software
will then gracefully shut the system down (confirm shut down with user, sync hard
drives, then turn off power supply). If the software is hung, the switch has a second
mode. If the switch is held down for 4 seconds, the switch will turn the power
supply off directly (independent of software).
C.5.1.1 Power-On
There are two conditions that will turn the system power on through the power on/
off control circuitry on the Sun Blade 100 motherboard.
■
The system was originally turned off and the front panel power on/off button is
pushed.
■
When the system was gracefully shutdown, and the alarm inside TOD M48T59
went off.
C.5.1.2 Power-Off
There are two conditions that will turn off the system power through the power on/
off control circuitry on the Sun Blade 100 motherboard.
■
The system shuts down through the Operating System: one general purpose
output pin of the SouthBridge will be activated to shut down the power supply.
■
When the system power was on, and front panel power on/off button is pressed
for more than 4 seconds.
C.5.2 On-Board VRM
The CPU requires two different voltage sources, 3.3V with 5% tolerance and 1.7V
with 3% tolerance. The total estimated power consumption is around 15 Watts at 500
MHz speed. The 3.3V source for the processor will be provided by the power supply
and the 1.7V source of the processor will come from an on-board voltage regulator.
The Raytheon RC5057 is the switcher control chip.
C.5.2.1 On-Board VRM requirements
The overall solution for the system on-board VRM should be based on the following
requirements,
■
Programmable output from 1.3V to 3.5V
■
5V input source
■
At least 12.5 amps driving capability