Electronic Design

HyperTransport 3.0: The Third Time's The Charm

HyperTransport's third time around adds more robust performance and features to an already successful run. The new standard not only extends HyperTransport's range and throughput, it also moves it into high-reliability environments that require features such as hot-swapping and power management.

Not surprisingly, HyperTranport 3.0 raises the link speed with a top end of 2.6 GHz. It remains backward-compatible with the 1.0 and 2.0 standard devices. Version 2.0 introduced doubledata-rate transfers, so the latest 3.0 high point is 20 Gbytes/s per link.

Auto negotiation handles differences between devices. This becomes more important with the addition of features like hot-swapping and the power-management mode, since device operation and connectivity can change over time.

Hot-swap support is key to Hyper-Transport's success in many applications, including its latest foray into mezzanine cards and potential new standardsin areas like MicroTCA. With it, high-performance processors and devices can be added to and removed from a system as necessary.

The AC mode extends HyperTransport across the backplane. Its new signaling convention slows down the overall transfer rate by a small amount while permitting much longer distances. It also is less susceptible to noise. The mode uses AC coupling capacitors and 8B/10B signaling. Devices automatically detect whether AC mode or the standard DC mode is in use. Both modes now handle multibit skewing.

The new Ganging Mode lets a 3.0 device with a 16-bit link split the connection into a pair of 8-bit links. This is handy when interfacing a pair of 8-bit peripherals to a host without the need for a switch.

See Associated Table

HyperTransport Consortium
www.hypertransport.org

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