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.
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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

Technologies

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

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Data Sheet (1)

Document NameDescriptionVersionLast Updated
Si3402.pdf
Si3402 Data Sheet1.311/20/2012

User Guides (2)

Document NameDescriptionVersionLast Updated
Si3402evb.pdf
Si3402 EVB User Guide1.03/10/2010
si3402iso-evb.pdf
Si3402ISO EVB User Guide1.16/10/2010

Application Notes (6)

Document NameDescriptionVersionLast Updated
AN296.pdf
AN296: Using the Si3402 POE PD Controller in Isolated and Non-Isolated Designs1.26/10/2010
AN313.pdf
AN313: Using the Si3402 in High Power Applications1.17/8/2010
AN314.pdf
AN314: Power Combining Circuit for PoE for up to 18.5 W Output1.06/7/2010
AN315.pdf
AN315: Robust Electrical Surge Immunity for PoE PDs through Integrated Protection0.46/7/2010
AN331.pdf
AN331: Compensating the Feedback Loop for the Si34021.06/7/2010
AN525.pdf
AN525: Optimized Class 1 PD Designs Using the Si34020.27/21/2011

White Papers (1)

Document NameDescriptionVersionLast Updated
Integrating-FETs-for-Power-over-Ethernet-Applications.pdf
Integrating FETs for Power over Ethernet Applications

Miscellaneous (2)

Document NameDescriptionVersionLast Updated
Si3402SwitcherCalcs.xls
Si3402 Switcher Calculator0.24/12/2012
Si3402-UNH-Reports.zip
Si3402 UNH Reports0.17/3/2010

PCN (9)

Document NameDescriptionVersionLast Updated
1110051 C-Pak as a Tape and Reel Supplier std.pdf
1110051 C-Pak as a Tape and Reel Supplier std
1202022B Si3402 Rev1.2 Datasheet Release Bulletin.pdf
1202022B Si3402 Rev1.2 Datasheet Release Bulletin
1211202-Si3402-Datasheet-Revision-v1.3.pdf
1211202 Si3402 Datasheet Revision v1.3
1303081-Si3460-1-Port-PSE-Interface-Not-Recommended-for-New-Designs.pdf
1303081 Si3460-1 Port PSE Interface Not Recommended for New Designs
1104011-Cancelled-ASEKR Die Bond Adhesive – Japan Earthquake and Tsunami Disaster Recovery.pdf
Cancelled-ASEKR Die Bond Adhesive – Japan Earthquake and Tsunami Disaster Recovery
1012161.pdf
Si3402 Datasheet Rev 1.1 Std
1006281.pdf
Si3402-A-GM Test Site Expansion-ASECL Std
1012231.pdf
Si3402-A-GMR Pin 1 Orientation Change Std
1007091.pdf
Si3460 Datasheet Rev 1.1 Std

Design Tools

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Schematics/Layout (2)

Document NameDescriptionVersionUpdated
Si3400ISO-EVB, Si3401ISO-EVB (Isolated EVBs).zip
Si3400 Isolated EVB Database1
Si3400-01-EVB-NonISO.zip
Si3400 Non-Isolated EVB Database1

Product Matrix

Product Matrix
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Part Number Available DocumentsTemperature RangeDescriptionPackage TypeMaximum Output Power
Si3402BuyData Sheet
-40 to 85 °CPD I/F with PWM controller and Low-EMIQFN2017 W
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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