Power/Cooling Module (Pcm); Requirements For Redundant Power; Figure 7-5 Pcm - Sun Microsystems Enterprise 6500 Reference Manual

7.4

Power/Cooling Module (PCM)

The power/cooling module (PCM) provides power for two boards. The PCM also
supplies cooling air to the board slots, so in normal operation each board must be
next to a working PCM.
FIGURE 7-5
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.
7.4.1

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 system needs a minimum of three power supplies and
four are present, then the system has redundancy. However, fully configured
Enterprise systems represent a different situation and are always hot-pluggable.
That is, an Enterprise 5500 or 4500 system with seven or eight boards and four PCMs
is hot-pluggable. (The peripheral power supply acts as the "extra" power supply.)
Similarly, an Enterprise 6500 system with fifteen or sixteen boards and eight power
supplies is also hot-pluggable. (Seven PCMs are sufficient to power sixteen active
boards; the eighth PCM is "extra." However, the eighth PCM is required for cooling
purposes.) See
7-8 Sun Enterprise 6500/5500/4500 Systems Reference Manual • April 1998
PCM
.
TABLE 7-3