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Cooling Requirements
The Motorola MVME162LX VME 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
VME system chassis. Load boards are inserted 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 that 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 (refer to Elevated-Temperature Operation below), 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
MVME162LX may subject it to high temperatures.
Introduction
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1-9
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