Motorola MVME167 Series, User Manual

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Specifications
MVME167/D3 1-3
1
Specifications
General specifications for the MVME167 are listed in Table 1-2. MVME167
Specifications on page 1-4.
The following sections detail cooling requirements and FCC compliance.
Cooling Requirements
The Motorola MVME167 VMEmodule 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 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.