Silicon Labs' integrated PD controller targets streamlined PoE

June 13, 2006 -- The company says its Si3400 PD controller enables PoE system designers to focus on system-level product differentiation and customization.

Silicon Laboratories has introduced what it calls one of the industry's most highly integrated, IEEE 802.3af compliant Power over Ethernet (PoE) controllers for powered device (PD) applications. The company says its Si3400 is the only PD controller to integrate on-chip diode bridges, a transient surge suppressor, and a switching regulator field effect transistor (FET).

The company says the Si3400 controller's "unprecedented level of integration" simplifies PoE design efforts by dramatically reducing the total bill of materials (BOM) and printed circuit board (PCB) area, as well as time to market. Designed for use in wireless access points (WAP), voice over IP (VoIP) phones, radio frequency identification (RFID) tag readers, point-of-sale terminals, security systems and cameras, the company says the controller can eliminate up to 25 external components compared to competing solutions, reducing PCB footprint by 30 to 50 percent and total BOM by as much as $1.50.

The company says the Si3400 enables PoE system designers to focus on system-level product differentiation and customization rather than spending time and resources fretting over external components and design issues such as analog layout or meeting radiated emissions specifications.

"The Si3400 represents the first product in our PoE family," said Dave Bresemann, vice president of Silicon Laboratories. "Our extensive high-voltage design experience has enabled us to solve several board-level analog design challenges, which will help lower costs and accelerate the adoption of PoE technology in a wide array of end products."

The company says it achieved such a high level of integration in the Si3400 by leveraging high-voltage and mixed-signal design expertise to deliver a versatile architecture that's fully compliant with IEEE 802.3af, while adding features beyond the standard's base requirements. For example, with direct access to the line side voltages from the Ethernet cable, the controller's integrated diode bridges enable a proprietary early power loss indicator, which provides adequate time to save operating and status information before safely shutting down the powered device. The diode bridges also allow a direct connection to the RJ-45 connector, which minimizes the PCB trace lengths between the connector and the Si3400; this helps to limit radiated emissions, speeding certification required by PoE products. In addition, the integrated transient suppressor activates protection circuitry when high voltages are detected, improving overall device reliability, according to the company.

The Si3400 controller includes a complete PD interface with programmable classification and detection signature circuitry, a switching regulator controller, dual current-limited hot swap switch, as well as protection circuitry including thermal shutdown capability and support for both non-isolated and isolated applications. The controller has been designed to operate seamlessly with both 802.3af compliant power sourcing equipment (PSE) and pre-standard (legacy) PSEs that do not comply with the standard's inrush current limits.

Pricing for the Si3400 begins at $2.48 in quantities of 10K. The controller is housed in a lead-free (RoHS-compliant), 5 x 5-mm, 20-pin QFN package. Samples are available, with production is scheduled for Q3 2006.

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