Motorola MVME162, User Manual

Page: 18 / 106

General Information
1-4 MVME162 Embedded Controller User’s Manual
1
Cooling Requirements
The Motorola MVME162 Embedded Controller is specified, designed, and
tested to operate reliably with an incoming air temperature range from 0° to
55° C (32° to 131° F) with forced air cooling at a velocity typically achievable
by using a 100 CFM axial fan. Temperature qualification is performed in a
standard Motorola VMEsystem 3000 chassis. Twenty-five watt load boards
are inserted in two card slots, one on each side, adjacent to the board under
test, to simulate a high power density system configuration. An assembly of
three axial fans, rated at 100 CFM per fan, is placed directly under the VME
card cage. The incoming air temperature is measured between the fan
assembly and the card cage, where the incoming airstream first encounters the
controller under test. Test software is executed as the controller is subjected to
ambient temperature variations. Case temperatures of critical, high power
density integrated circuits are monitored to ensure component vendors
specifications are not exceeded.
While the exact amount of airflow required for cooling depends on the
ambient air temperature and the type, number, and location of boards and
other heat sources, adequate cooling can usually be achieved with 10 CFM
and 490 LFM flowing over the controller. Less airflow is required to cool the
controller in environments having lower maximum ambients. Under more
favorable thermal conditions, it may be possible to operate the controller
reliably at higher than 55° C with increased airflow. It is important to note that
there are several factors, in addition to the rated CFM of the air mover, which
determine the actual volume and speed of air flowing over the controller.
Special Considerations for Elevated Temperature Operation
The following information is for users whose applications for the MVME162
may subject it to high temperatures.
The MVME162 uses commercial grade devices. Therefore, it can operate in an
environment with ambient air temperatures from 0° C to 70° C. Several factors
influence the ambient temperature seen by components on the MVME162.
Among them are inlet air temperature; air flow characteristics; number, types,
and locations of IndustryPack (IP) modules; power dissipation of adjacent
boards in the system, etc.
A temperature profile of the MVME162-023 was developed in an MVME945
12-slot VME chassis. This board was loaded with one GreenSpring IP-Dual
P/T module (position a) and three GreenSpring IP-488 modules (positions b,
c, and d). One twenty-five-watt load board was installed adjacent to each side
of the board under test. The exit air velocity was approximately 200 LFM