11990-704/705/706/707 (2-Slot ATCA Shelf)
Fan Trays
13
R1.2, March 2018
7.1 IPM Controller and Fan Control
The on-board IPM controller is located on the Fan Tray and has 2 operation modes:
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 specified speed by Shelf Manager. The circuitry on-board 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.
The system is designed to run indefinitely with any single fan failure. When one fan fails, all
other fans are increased to full speed. The Fan Tray has sufficient cooling capacity to keep the
Shelf cooled with a single fan failure.
2. Autonomous Mode
When no Shelf Manager is present, the Fans are controlled by the IPM controller. The fan
speed depends on the setting of DIP switch on the controller board. With a Micro DIP switch
you can select either the exhaust temperature from the left Fan Tray as reference to control
the fan speed or fixed fan speed.
Table 3: Micro DIP switch settings
Bit 1
Bit 2
Bit 3 Description
0
0
0
Fixed Speed, 50% of Full Speed
0
0
1
Fixed Speed, 70% of Full Speed
0
1
0
Fixed Speed, 90% of Full Speed
0
1
1
Fixed Speed, 100% of Full Speed
1
0
0
Exhaust Temperature 35 ~ 45 °C
1
0
1
Exhaust Temperature 40 ~ 50 °C
1
1
0
Exhaust Temperature 45 ~ 55 °C
1
1
1
Exhaust Temperature 50 ~60 °C
The default setting is 50% of full speed.
