Electronic Design

IC Transceivers Raise CompactPCI Slot Count And Clock Rate

Fairchild Semiconductor has boosted the performance of the popular CompactPCI backplane by expanding it from eight to 21 slots. This increase is based on work at EnSigna Labs, which is part of Fairchild's Interface and Logic Group in South Portland, Maine.

The lab employed the company's enhanced gunning transceivers to produce an incident-wave switching design. No bridging was necessary to expand its usual eight-slot configuration to 21 slots. With the possible exception of expanding the slot address space, no changes to the CompactPCI specification's timing or basic protocol were required to realize full 21-slot utilization, either. Likewise, the CompactPCI specification can be supported with 15-slot operation at 66 MHz. Previously published attempts have confined 66-MHz operation to no more than a five-slot configuration.

Some of the enhanced gunning transceivers' unusual characteristics make these performance improvements possible. The transceivers feature high drive and low swing—less than 1 V. Additionally, they incorporate edge-rate control, which permits very fast swings through the transition period. Edge-rate control also removes the corner points that are rich in high harmonic frequencies, thereby diminishing noise and ringing.

These characteristics, together with some additional optimization capabilities, enable these devices to achieve incident-wave switching with a greater slot count and a higher clock rate in a CompactPCI backplane environment.

For more information, contact Fairchild Semiconductor at (888) 522-5372, or go to www.fairchildsemi.com.

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