Power/Cooling Module (Pcm); Requirements For Redundant Power; Figure 7-6 Pcm - Sun Microsystems Enterprise 3500 System Reference Manual

7.5

Power/Cooling Module (PCM)

The power/cooling module (PCM,
PCM also supplies cooling air to the board slots, so in normal operation each board
must be next to a working PCM.
FIGURE 7-6
The PCM incorporates an AC inrush limit circuit and two precharge inputs (3.3V
and 5V) that enable it to be hot-pluggable into a live centerplane.
Within a system all PCMs operate in a parallel redundant mode, sharing 2.0V, 3.3V,
and 5V output currents. The shared 5V output also includes the 5V output of a
peripheral power supply.
7.5.1

Requirements for Redundant Power

If a DC supply in a PCM fails, the system boards will continue to be powered and
cooled by the other power supplies if sufficient redundancy (an additional power
supply) is present.
For example, if an Enterprise 3500 system needs a minimum of two PCMs and three
are present, then the system has redundancy (
Note – The presence of an additional (extra) PCM in the system provides
redundancy and allows hot-plug of PCMs. When all five board slots are populated, there
is no redundancy because of the two PCMs per board rule.
PCM
) provides power for two boards. The
FIGURE 7-6
Quarter-turn
access slot
Extraction lever
).
TABLE 7-3
Chapter 7 Power Supplies 7-11