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Appendix E: Challenge VMEbus Implementation
VME Board Dimensions
Deskside VME Power and Cooling
Exceeding the Normal VME Power Rating Per Slot
134
The Challenge board slots have a 9U (vertical) form factor and measure 15.75
inches (400 mm) horizontally. The board edges must also be less than or
equal to 0.062 inches (1.57 mm). If the board is thicker, the edge of the board
must be milled to fit in the card guide. In addition, center-to-center board
spacing is 0.8 inch (20.3 mm).
The deskside Challenge provides five 9U VME slots. The system supplies
approximately 40 watts of 5 V power per VME slot (nominally). The system
provides 16.7 amps of 12 V power for the entire chassis. This provides
approximately 0.25 to 0.5 amps (or 3 to 6 watts) per VME slot.
The deskside chassis circulates approximately 150 to 250 linear feet per
minute (LFM) of air flow through the chassis (depending on the ambient
temperature).
If a VME board requires more than the normal slot power allotment, it is still
possible the board can be used. However, two factors need to be carefully
addressed—proper air flow and total power used.
To help maintain proper cooling, the board may also need special custom
baffles, or perhaps a set of non-component, enclosure boards to surround the
VME board with sufficient air flow. These custom air flow devices must be
supplied by the customer.
A third-party VME board requiring greater than 40 watts of 5 V power can
be used, as long as the board does not draw more than the amount of power
allocated for VME board use. Generally speaking, this amount is
approximately 150 watts of 5V power.
For example, you can install two 75-watt VME boards in a deskside system
(providing the boards were sufficiently cooled). However, as a result, you
could not install any additional VME boards, since the VME power
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