Sun Microsystems 5500, Reference Manual

Page: 117 / 304

Chapter 7 Power Supplies 7-3
7.2 Power Distribution
The system has a single peripheral power supply, and each pair of board slots has a
slot for a PCM. AC is distributed to each of the PCMs within the chassis. The
software monitors the status of the AC power source. Current-sharing between
power supplies provides redundant power.
7.3 Peripheral Power Supply
The peripheral power supply (
FIGURE 7-1
) provides power to the peripheral
subsystems, the drives, the fans in the AC box, and the fan in the key switch box.
The PPS provides auxiliary 5V output to power an optional remote console.
FIGURE 7-1
Peripheral Power Supply
The peripheral power supply provides three precharge outputs (3.3V, 5V, and 12V)
to enable hot plug-in of system boards, PCMs, or drives into an active centerplane.
The PPS shares current with PCMs on the 5V output at the centerplane. In this way
the PPS helps to reduce the possibility of a system failure if a PCM fails.