15
aTCA-80606PA
6 Fan Trays
6.1 Introduction
The 6 Slot ATCA Shelf contains two hot-swappable Fan Trays arranged in a side to side
configuration for maximum air flow. The Fan Trays are locked into the Shelf by a mini
compression latch with indicator. A hot swap push button is used to provide hot swap
functionality. The Fan Trays are intelligent FRUs and plugged in at the left and right front
of the Shelf.
Each Fan Tray contains six 92mm fans (245m
3
/h (146CFM) each). The Fan Tray is
controlled via an onboard IPM controller.
Figure 5: Fan Tray
1.
Fan Tray OK LED (green)
2. Fan Tray Fault LED (red)
3. Hot Swap LED (blue)
4. Hot Swap Push Button
5. Handle
6. Mini Compression Latch
6.2 Fan Control Model
The onboard IPM controller is located on the Fan Tray and has 2 operation modes:
6.2.1 Shelf Manager Mode
As soon as a Shelf Manager is plugged-in and becomes active, the IPM controller
switches automatically into the Shelf Manager mode. The Shelf Manager performs
management of the Fan Tray through the two independent bussed IPMB connections.
When the Fan Tray is first inserted into the system, the fans start at full speed and then
decrease to the specified speed by Shelf Manager. The circuitry onboard the Fan Tray
uses a PWM signal to control the speed of all the fans. Lower speeds reduce acoustic
noise and power consumption and increase the lifetime of the fans.
The speed of each individual fan is monitored. If any of the fan speeds drops below the
desired fan speed, a System Event Log (SEL) entry is logged by the Shelf Manager. The
Shelf Manager then generates alerts and sets alarm conditions as necessary.
