Cooling Requirements - Motorola MVME2700 Series Installation And Use Manual

Cooling Requirements

Cooling Requirements
B
B-2
The Motorola MVME2700 family of single-board computers 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 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 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 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 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 a
module.
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