US Patent 8345439 Modular chassis arrangement with redundant logic power delivery system

A modular packet network device has a chassis in which multiple logic cards mate to the front side of an electrical signaling backplane. Logic power for the logic cards is supplied from a group of power converter cards that convert primary power to the logic voltages required by the logic cards. The power converter cards lie in a separate cooling path behind the backplane. Advantages achieved in at least some of the embodiments include removing primary power planes from the signaling backplane or portion of the backplane, providing redundant, upgradeable power modules whose individual failure does not cause logic card failure, and providing cool air to power converter circuits that would be subject to only heated air if located on the logic cards. Other embodiments are also described and claimed.