Si3402

The Si3402 is the industry’s most highly-integrated, IEEE 802.3 clause 33 compliant, PoE PD interface and pulse-width-modulated (PWM) switching regulator. By setting a new bar for device integration, lowest overall BOM cost, efficiency and reliability, the Si3402 enables designers to easily add PoE functionality to their Ethernet products. When connected in a PoE-enabled system, such as a wireless access point or VoIP phone, the Si3402 converts the high voltage (typically ±48 V) supplied over Ethernet copper UTP cabling into a regulated, low-voltage dc supply. In addition, the Si3402 combines all the required IEEE 802.3 clause 33 detection, classification and hot swap interfaces with a complete, high efficiency, PWM switching regulator, including programmable soft start.

Compared to competing PD solutions, which typically require several external high-voltage discrete devices to complete a PD interface, the Si3402 uniquely integrates two full diode bridges, a transient voltage suppressor and a switching regulator driver FET on chip. Depending on the application’s power supply isolation requirements, the primary benefits of the Si3402’s unmatched integration level are:

Elimination of four critical high-voltage BOM components: Two full diode bridges, a transient voltage suppressor and a switching regulator driver FET

Reduction in external BOM savings of at least $0.30 to $0.40 USD

Reduction of typical PCB layout footprints of 30%

Direct connection to RJ-45 jack for reduced EMI

Simplified design, PCB layout and validation processes

Leveraging Silicon Labs' proven high voltage design and manufacturing expertise, the Si3402 also enables enhanced PoE functionality, such as intelligent, system-level circuit protection and an early power loss indicator for reliable shut down of the PD when power is lost.