Si3402 PoE PD Interface and Switching Regulator

The Si3402 is the industry’s most highly-integrated, IEEE 802.3af Type 1-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 included in the design of 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 802.3af Type 1 detection, classification and hot swap interfaces with a complete, high efficiency, PWM switching regulator.

The Si3402-B is a pin-compatible replacement for the End-of-Life Si3402-A. Existing customer products which were based on Si3402-A EVB reference designs can be readily re-used with minimal change to a few on-board components.


  • Supports non-isolated and isolated switching topologies
  • Fully integrated high-voltage devices
  • Two complete diode bridges
  • Transient voltage suppressor
  • Switching regulator driver FET
  • Dual current-limited hot swap switch
  • Comprehensive protection circuitry
  • Transient over-voltage protection
  • Under voltage lockout
  • Thermal shutdown protection
  • Fold back current limiting
  • Low-EMI slew rate control

Getting Started with Si3402B Powered Device

Si3402B Isolated PD Evaluation Kit

The easiest way to begin development with the Si3402B PoE Powered Device is with the Si3402B Isolated Evaliation Kit. A Non-Isolated version is also available.

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Si3402 Product Matrix

Part Number Data Sheet Evaluation Kit Description Temperature Range (ºC) Package Type Maximum Output Power (W)
Si3402BISO-EVB PoE PD Interface with DCDC Converter -40 85 QFN20 17
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