Description
The Si3454 is a fully-programmable, four-port power management controller for IEEE 802.3 compliant Power Sourcing Equipment (PSE). Designed for use in PSE endpoint (switches), the Si3454 integrates four independent ports, each with IEEE-required powered device (PD) detection and classification functionality. In addition, the Si3454 features a fully-programmable architecture that enables powered device (PD) disconnect using a dc sense algorithm, a robust multipoint detection algorithm, software-configurable per-port current and voltage monitoring, and programmable current limits to support the IEEE 802.3at standard. Intelligent protection circuitry includes input undervoltage detection, output current limit, and short-circuit protection. The Si3454 operates by host processor control through a three-wire, I2C-compatible serial interface. Independent serial data input and output pins enable high voltage isolation through external isolators. An interrupt pin is used to alert the host processor of various status and fault conditions. The device also supports a pin-selectable AUTO mode for autonomous operation, without the need for a host processor. The Si3454 also features an onchip dc-dc converter for creating the digital voltage rail from the PoE voltage, thus enabling single-rail power operation.

FEATUREs
■ Quad-Port Power Sourcing Equipment (PSE) controller
■ IEEE 802.3at Type I and II compliant
■ Port priority shutdown control
■ Adds enhanced features for maximum design flexibility:
• Per-port current and voltage monitoring
• PoE Plus support with programmable current limits
• Multi-point detection
• Programmable power MOSFET gate drive control
• Configurable watchdog timer enables failsafe operation
■ Maskable interrupt pin
■ Comprehensive fault protection circuitry includes:
• Power undervoltage lockout
• Output current limit and short circuit protection
• Thermal overload detection
■ Supports pin-selectable AUTO mode
■ Extended operating temp range: –40 to +85 °C
■ 5x7 mm 38-pin QFN package (RoHS-compliant)
■ On-chip dc-dc converter enables single-rail power operation

APPLICATIONs
■ IEEE Power Sourcing Equipment (PSE)
■ Power over Ethernet (PoE) Switches
■ IP Phone Systems
■ Smartgrid Switches
■ Ruggedized and Industrial Switches