LT4276 - LTPoE++/PoE+/PoE PD Forward/Flyback Controller


  • IEEE802.3af/at and LTPoE++™ 90W Powered Device (PD) with Forward/Flyback Controller
  • LT4276A Supports All of the Following Standards:
  • LTPoE++ 38.7W, 52.7W, 70W and 90W
  • IEEE 802.3at 25.5W Compliant
  • IEEE 802.3af up to 13W Compliant
  • LT4276B is IEEE 802.3at/af Compliant
  • LT4276C is IEEE 802.3af Compliant
  • Superior Surge Protection (100V Absolute Maximum)
  • Wide Junction Temperature Range (–40°C to 125°C)
  • Auxiliary Power Support as Low as 9V
  • No Opto-Isolator Required for Flyback Operation
  • External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency
  • >94% End-to-End Efficiency with LT4321 Ideal Bridge
  • Available in a 28-Lead 4mm × 5mm QFN Package

Typical Application

LT4276 Typical Application
LT4276 Typical Application


The LT®4276 is a pin-for-pin compatible family of IEEE 802.3 and LTPoE++ Powered Device (PD) controllers. It includes an isolated switching regulator controller capable of synchronous operation in both forward and flyback topologies with auxiliary power support.

The LT4276A employs the LTPoE++ classification scheme, receiving 38.7W, 52.7W, 70W or 90W of power at the PD RJ45 connector, and is backwards compatible with IEEE 802.3. The LT4276B is a fully 802.3at compliant, 25.5W Type 2 (PoE+) PD. The LT4276C is a fully 802.3af compliant, 13W Type 1 (PoE) PD.

The LT4276 supports both forward and flyback power supply topologies, configurable for a wide range of PoE applications. The flyback topology supports No-Opto feedback. Auxiliary input voltage can be accurately sensed with just a resistor divider connected to the AUX pin.

The LT4276 utilizes an external, low RDS(ON) N-channel MOSFET for the Hot Swap function, maximizing power delivery and efficiency, reducing heat dissipation, and easing the thermal design.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LT4276AHUFD#PBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4276AHUFD#TRPBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4276AIUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT4276AIUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT4276BHUFD#PBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4276BHUFD#TRPBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4276BIUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT4276BIUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT4276CHUFD#PBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4276CHUFD#TRPBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4276CIUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT4276CIUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes

LT4276 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LT4276AHUFD#PBF 4x5 QFN-28 H $5.31 $3.72 Yes
LT4276AHUFD#TRPBF 4x5 QFN-28 H $5.37 $3.78 Yes
LT4276AIUFD#PBF 4x5 QFN-28 I $4.43 $3.10 Yes
LT4276AIUFD#TRPBF 4x5 QFN-28 I $4.49 $3.16 Yes
LT4276BHUFD#PBF 4x5 QFN-28 H $4.46 $3.12 Yes
LT4276BHUFD#TRPBF 4x5 QFN-28 H $4.52 $3.18 Yes
LT4276BIUFD#PBF 4x5 QFN-28 I $3.71 $2.60 Yes
LT4276BIUFD#TRPBF 4x5 QFN-28 I $3.77 $2.66 Yes
LT4276CHUFD#PBF 4x5 QFN-28 H $3.60 $2.52 Yes
LT4276CHUFD#TRPBF 4x5 QFN-28 H $3.66 $2.58 Yes
LT4276CIUFD#PBF 4x5 QFN-28 I $3.21 $2.25 Yes
LT4276CIUFD#TRPBF 4x5 QFN-28 I $3.27 $2.31 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC2046A-A LT4276B/LT4321 Demo Board | PoE+ (25W, 3.3V/6.8A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2046A-B LT4276B/LT4321 Demo Board | PoE+ (25W, 5V/4.7A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2046A-C LT4276B/LT4321 Demo Board | PoE+ (25W, 12V/1.9A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2046A-D LT4276B/LT4321 Demo Board | PoE+(25W, 24V/1A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2046A-E LT4276A/LT4321 Demo Board | LTPoE++ (38.7W, 5V/7A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2046A-F LT4276C/LT4321 Demo Board | PoE (13W, 5V/2.3A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2047A-A LT4276B/LT4321 Demo Board | PoE+ (25W, 12V/1.9A) PD with DC/DC, Ideal Diode Bridge and 9V-57V AUX $95.00
DC2262A-A LT4276A/LT4321 Demo Board | LTPoE++ (70W, 5V/13A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2262A-B LT4276A/LT4321 Demo Board | LTPoE++ (90W, 12V/7A) PD with DC/DC and Ideal Diode Bridge $95.00
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Companion Boards

Part Number Description Price Documentation
DC1814A-A LTC4274A-1 Demo Board | LTPoE++ (38.7W) PSE $100.00
DC1815A-A LTC4266A-1 Demo Board | 4-Port 38.7W LTPoE++ PSE (req. DC590) $200.00
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Click here to view our complete list of demo boards


  • High Power Wireless Data Systems
  • Outdoor Security Camera Equipment
  • Commercial and Public Information Displays
  • High Temperature Applications

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