Flexible switch has 48 lanes
By Richard A Quinnell, Contributing Technical Editor -- EDN, October 2, 2006
Switches are a key component of systems based on the emerging PCIe (PCI Express) standard. The more capable the switch, the more design flexibility that developers enjoy. PLX Technology has now introduced one of the most flexible PCIe switches currently available, the PEX 8548. This device offers 48 PCIE lanes that designers can allocate across as many as nine ports in a wide variety of configurations.
The PEX 8548 targets high-performance graphics and PCIe fan-out applications, but its flexibility makes it suitable for a variety of designs. It has nonblocking switch architecture, enabling it to offer peer-to-peer transfers that can operate in parallel with other transfers through the switch. Cut-through latency is less than 110 nsec. The nine ports are configurable, allowing users to allocate the 48 available lanes as one, two, four, eight, or 16 ports. Thus, for graphics applications the device can offer three 16-lane ports. As a fan-out switch, it can offer six eight-lane ports, four four-lane ports, four eight-lane ports, or many other combinations.
The device complies with PCIE 1.1, and three of its ports support hot plug operation. It offers a JTAG interface for test and I2C for out-of-band control. An EEPROM for power-up configuration is available as an option. The device costs $65 (high volumes), will be available for sampling in the fourth quarter, and should be in full production in early 2007.
