Cooling Requirements - Motorola MVME2603-1121A Installation And Use Manual

Cooling Requirements

Cooling Requirements
B
B-2
The Motorola MVME2603/2604 family of Single Board Computers
is specified, designed, and tested to operate reliably with an
incoming air temperature range from 0û to 55û C (32û to 131û F) with
forced air cooling of the entire assembly (base board and modules)
at a velocity typically achievable by using a 100 CFM axial fan.
Temperature qualification is performed in a standard Motorola
VMEsystem 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 module under test. Test
software is executed as the module is subjected to ambient
temperature variations. Case temperatures of critical, high power
density integrated circuits are monitored to ensure component
vendorsÕ 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 module. Less
airflow is required to cool the module in environments having
lower maximum ambients. Under more favorable thermal
conditions, it may be possible to operate the module reliably at
higher than 55û 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 a module.