Service manual

Power System 4-5
The power control module performs the following functions:
• Controls the power-up/down sequencing.
• Monitors the combined output of power supplies VDD (3.43V) and VCC (5.0V)
and asserts DCOK_SENSE if these voltages are within range and asserts
POWER_FAULT_L causing an immediate power shutdown if either is not.
• Monitors system temperature and asserts TEMP_FAIL, if temperature exceeds
55° C.
• Monitors CPU and system drawer fans and asserts CPUFAN_OK if all CPU fans
are functioning properly, asserts SYSTEM_FAN_OK if the drawer cooling fans
are functioning properly; otherwise it asserts FAN_FAULT_L. Each fan is
checked at 1 second intervals.
• Powers down the system 30 seconds after detecting TEMP_FAIL, or the absence
of CPUFAN_OK, or the absence of SYSTEM_FAN_OK by asserting
POWER_FAULT_L.
• Provides visual indication of faults through LEDs.
• Has two registers, one that generates interrupts when bits change, and one that
latches errors but does not generate interrupts.