Cooling Requirements; Emc Compliance - Motorola MCP750 Installation And Use Manual

Specifications
A

Cooling Requirements

EMC Compliance

A-2
The Motorola MCP750 family of Single Board Computers is specified,
designed, and tested to operate reliably with an incoming air temperature
range from -5° 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
CompactPCI 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 CompactPCI 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.
The MCP750 Single Board Computer was tested in an EMC-compliant
chassis and meets the requirements for EN55022 Class B equipment.
Compliance was achieved under the following conditions:
Shielded cables on all external I/O ports.
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