Motorola MVME162 manual Special Considerations for Elevated Temperature Operation

Introduction 1

Special Considerations for Elevated Temperature Operation

The following information is for the user who has an application for the

MVME162 which will subject it to high temperature.

The MVME162 uses commercial grade devices. Therefore, it can operate in an environment with ambient air temperature from 0° C to 70° C. There are many factors that affect the ambient temperature seen by components on the MVME162: inlet air temperature; air flow characteristics; number, types, and locations of IndustryPack (IP) modules; power dissipation of adjacent boards in the system; etc.

A temperature profile was performed for the MVME162-23 in an MVME945 12-slot VME chassis. This board was loaded with one GreenSpring IP-Dual P/T module (position a) and three GreenSpring IP-488 modules (positions b, c, and d). One twenty-five watt load board was installed adjacent to each side of the board under test. The exit air velocity was approximately 200 LFM between the MVME162 and the IP-Dual P/T module. Under these circumstances, a 10° C rise between the inlet and exit air was observed. At 70° C exit air temperature (60° C inlet air), the junction temperatures of devices on the MVME162 were calculated (from the measured case temperatures) and do not exceed 100° C.

Caution

For elevated temperature operation, the user must perform similar measurements and calculations to determine what operating margin exists for any specific environment.

The following are some steps that the user can take to help make elevated temperature operation possible:

1.Position the MVME162 board in the chassis for maximum airflow over the component side of the board.

2.Avoid placing boards with high power dissipation adjacent to the MVME162.

3.Use low power IP modules only. The preferred locations for IP modules are position a (J2 and J3) and position d (J18 and J19).

MVME162IG/D2 1-7