Silicon Labs Power Management ICs Reduce Power for Power over Ethernet Equipment
Silicon Laboratories Inc. introduced the Si348x family of power management ICs, enabling reduced system cost and improved efficiency in power over Ethernet (PoE) power sourcing equipment (PSE). Complementing Silicon Labs’ Si3452 PSE controllers, the new PoE power management ICs provide an easy-to-use, energy-efficient and small-footprint solution for streamlining power delivery in managed and unmanaged switches and routers, iPBXs, IP-based security systems, set-top boxes and power injectors.
Efficient, intelligent and cost-effective balancing of powered device (PD) loads is a critical design consideration for multi-port PoE equipment. For example, the PoE+ standard allows up to 30W per port to be sourced by the PSE, requiring 720 total Watts in a 24-port system. At any given time, some or perhaps most of these ports may not be in use or drawing full power. The ability to properly size the power supply through active power management enables dramatic power supply cost savings and higher system efficiency. Silicon Labs’ Si348x power management ICs take advantage of the real-time voltage and current monitoring capabilities of the Si3452 PoE controller to apply active power management based on actual consumption, enhancing the efficient use of switch ports beyond simple classification schemes.
For compact systems of eight ports or less, the Si3480 power manager provides a pin-programmable, stand-alone solution that does not require an interface to an intelligent host, making it ideal for unmanaged switches or other applications in which the user wants full-featured active power management without having to write or integrate system software.
For larger PoE systems, the Si3482 power manager leverages the real-time voltage and current monitoring capability of the Si3452 controller to manage up to 48 ports with as many as three power sources. The Si3482 device can be programmed by its host via a serial peripheral interface (SPI) or universal asynchronous receiver/transmitter (UART) interface, setting the power supply capacity, port power configuration, port priority, detection timing and fault recovery protocol. Once programmed, the Si3482 can operate without host intervention using the saved configuration data. The Si3482 also facilitates link layer discovery protocol (LLDP) agents in the host, which can call a routine in the Si3482 to dynamically adjust the amount of power granted to a PD during the course of a connection.
"Our innovative approach to active power management reduces PoE system cost by allowing designers to right-size power supplies in both managed and unmanaged switch products, avoiding costly overdesign," said Carlos Garcia, Vice President of Wireline Products at Silicon Laboratories. "Silicon Labs’ end-to-end PoE solutions are based on an integrated systems-level approach, giving designers the ability to optimize their applications for power efficiency while reducing BOM costs and board space."
The Si3480 8-port power management IC is available in a 20-pin, 4 x 4mm QFN package. Pricing for the Si3480 begins at $0.93 (USD) in 10,000-unit quantities. The Si3482 48-port power management IC is available in a 20-pin, 4 x 4mm QFN package. Pricing for the Si3482 begins at $2.40 (USD) in 10,000-unit quantities. The Si348x devices are companion chips to Silicon Labs’ IEEE 802.3at-compliant Si3452 controller available in RoHS-compliant, 6 x 6mm QFN packaging and priced at $3.40 (USD) in 10,000-unit quantities.
