VITA membership to write new CompactPCI standards

SCOTTSDALE, Ariz. — Members of the VME International Trade Association (VITA) for the first time are writing a standard for convection- and conduction-cooled CompactPCI.

Jul 1st, 1999

By John McHale

SCOTTSDALE, Ariz. — Members of the VME International Trade Association (VITA) for the first time are writing a standard for convection- and conduction-cooled CompactPCI.

"The war [between CompactPCI and VME] is over," claims Doug Patterson, military marketing manager at SBS Embedded Computers in Warrenton, Va., and writer of the CompactPCI conduction-cooled standard.

It may be over to a point, says Ray Alderman, executive director for VITA, but there still remain differences in the technology.

However, the VITA membership, which includes companies that produce CompactPCI, wanted to cool the heated debate between supporters of the two tech- nologies, Alderman says.

The standard for convection-cooled focuses on 3U, 6U, and 9U CompactPCI boards and is 98 percent finished with completion expected by the end of this year, Alderman says. The conduction-cooled standard is just getting started and will be finished toward the end of next year.

Chairing the VITA committee overseeing the standard is Richard Somes, technical director of OEM Business at Compaq in Houston and vice president for technology for the PCI Industrial Computer Manufacturers Group (PICMG) in Wakefield, Mass. Somes serves as the liaison between VITA and PICMG, Alderman says.

Patterson is rewriting the VITA 1101.2 standard for conduction-cooled VME to apply it to CompactPCI. The only difference between the two standards involves identifying the dimension between the thermal interface and the centerline of connectors, he says.

Understanding the thermal cores and how they work will be difficult, but once that is done the procedure is pretty straightforward, Patterson explains.

Alderman says he believes that the new CompactPCI standard will cause problems because it cannot be as flexible the VME 1102.1 standard. The VME standard allowed for the space between the boards on a rack to be less than .8 inches.

However, because the connectors on a CompactPCI board go all the way to the end of the board, engineers are precluded from using less than .8 inches, Patterson says.

Patterson says he believes this will not be a problem because the boards fit easily into their slots and most everyone uses the .8-inch distance.

SBS engineers already design conduction- and convection-cooled CompactPCI with their CR6 and CR7 boards.

The CR6 rugged 6U board is conduction cooled with an extended temperature range of -40 to 85 degrees Celsius, and resists the effects of shock and vibration by employing stiffener bars, wedge locks, and conformal coating. The board works with Intel Pentium and AMD K6 processors. The CR7 works with the Pentium II.

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