Si3402 PD Interface and Switching Regulator

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.
 
 

Features

  • 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
 
 

Applications

Documentation

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Data Sheet (1)

User Guides (2)

DescriptionVersionUpdatedSize
Si3402 EVB User Guide
1.03/10/2010274 kB
Si3402ISO EVB User Guide
1.16/10/2010289 kB

Application Notes (6)

White Papers (1)

Miscellaneous (2)

DescriptionVersionUpdatedSize
Si3402 Switcher Calculator
0.24/12/201223 kB
Si3402 UNH Reports
0.17/3/2010819 kB

PCN (10)

Design Tools

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Schematics/Layout (2)

DescriptionVersionUpdatedSize
Si3400 Isolated EVB Database
11552 kB
Si3400 Non-Isolated EVB Database
11437 kB
Product Matrix
Zoom
Part NumberTemperature RangeDescriptionPackage TypeMaximum Output Power
Si3402-40 to 85 °CPD I/F with PWM controller and Low-EMIQFN2017 W

Technologies

  • Complete IEEE 802.3af compliant PD interface, hot swap controller and efficient PWM switching regulator
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 regulator'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.

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