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Cooling Requirements
The PrPMC750 module is specified, designed, and tested to operate
reliably when mounted on a carrier board with an incoming air temperature
range from 0
typically achievable by using a 100 CFM axial fan.
Temperature qualification is performed in a standard Motorola
VMEsystem chassis. Thirty-six 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 two axial fans, rates
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 in order to exercise the board under test.
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 450 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
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.
http://www.motorola.com/computer/literature
º
º
º
º
to 55
C (32
to 131
º
C with increased airflow.
F) with forced air cooling at a velocity
Specifications
B
B-3
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