Electronic Design

Next-Generation Ethernet PHY Chip Breaks Power And Performance Barriers

We often take Ethernet physical-layer (PHY) chips for granted. But with 1-Gbit Ethernet (1GE) moving into the PC mainstream, it's time to give them another look. As a member of the SimpliPHY line of next-generation Ethernet chips, Vitesse Semiconductor's VSC8601 meets the triple-play (voice, video, and data) challenges.

With the highest integration of any PHY available and lowest power, the VSC8601 is a great candidate for the Gigabit LAN on motherboard (GLOM) trend in laptops and PCs. Still, it's a classic PHY chip. It talks to the mediaaccess controller (MAC) chip via a reduced gigabit media-independent interface (RGMII) and directly to the CAT5/6 twisted pair through the external magnetics.

According to Sean Michaud, director of business development for Vitesse's Ethernet Products Division, the VSC8601 has the lowest power consumption—600 mW—of any currently available PHY chip. That's a 25% reduction in power over competitive solutions. Plans call for even less power in the near future.

The chip's internal line termination resistors eliminate the need for external resistors and the board space they consume. Plus, an internal 1.2-V regulator further reduces the need for additional parts. Its integrated RGMII timing compensation eliminates the need for onboard delay lines as well.

The chip uses Vitesse's patented voltage-mode technology instead of the current-mode approach everyone else uses. And according to the company, the VSC8601 delivers best-in-class noise performance in real-world PC boards and cables.

The VSC8601 is supported by Vitesse's VeriPHY cable diagnostics and a full suite of loopback mode tests, as well as digital and analog built-in self-test and a JTAG interface. Made from 0.13-µm CMOS, the chip comes in a 64-pin exposed-pad lowprofile quad-flat package (EP-LQFP). It operates from 3.3 V.

A variation of this part, the VSC8641, fits Gigabit Ethernet Passive Optical Network (GE PON) applications. The chip offers both RGMII as Qwell as the GMII interfaces in addition to all of the VSC8601's features. The package is a 100-pin EP-LQFP.

Shipping now, the VSC8601 and the VSC8641 both are available in volume production.

Vitesse Semiconductor Corp.

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