Low-lane-count PCIe switch ventures into new applications
By Jeff Berman, News Editor -- EDN, August 19, 2005
PLX Technology this week introduced a five-port, eight-lane PCI Express (PCIe) switch for applications like high-end printers, multichannel network adapters, and notebook docking stations.
The PEX 8508 complies with PCI Express Specification R1.1 and offers engineers previously unavailable configuration options, along with a reduced footprint and lower power and cost, according to the company.
"This is the first low-lane-count switch on the market," said John Gudmundson, the company's senior marketing manager. "Having an odd number of ports provides an advantage, because it is compatible with our previous switches." The list of compatible devices includes the 8524, 8516, and 8532, he added.
The PEX 8508 presents a compelling choice compared with competing devices that have more lanes than are required and, in some cases, not enough ports, Gudmundnson said. As the first offering of the company's second generation of switches, the PEX 8508 reduces packet latency to less than 150 nsec, he said.
Notable features of the switch include: an I2C bus, fatal-error signal support, ISA/VGA-enable registers for graphics applications, four general-purpose I/Os, the ability to go into an ultralow-power state and wake up via in-band or out-of-band signaling, hot-plug controllers on all ports, and support for constant frequency and spread-spectrum clocking.
The PEX 8508 specifically targets add-in-card applications such as Ethernet aggregation and processor isolation, Gudmudnson noted. "We are starting to see that the market for these high-end adapter cards is growing, and it is almost becoming required that these cards have multiple I/Os on them," he said. "But the costs cannot be significant for them to be heavily adopted."
One of the biggest markets for the PEX 8508 is processor isolation. "When isolation processors are on separate cards, there is lower latency," Gudmudnson said. "If a board or processor goes down, you need the other one to quickly take over, and that requires low latency through the switch."
The PEX 8508 comes in a 19×19-mm, 273-pin PBGA package and will begin sampling during the fourth quarter. It will cost less than $15 in volume quantities. A Rapid Development Kit will sell for $995.
