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

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.

  • 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

  • High Power Wireless Data Systems
  • Outdoor Security Camera Equipment
  • Commercial and Public Information Displays
  • High Temperature Applications
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LT4276AHUFD#PBF4x5 QFN-28H$5.31$3.72
LT4276AHUFD#TRPBF4x5 QFN-28H$5.37$3.78
LT4276AIUFD#PBF4x5 QFN-28I$4.43$3.10
LT4276AIUFD#TRPBF4x5 QFN-28I$4.49$3.16
LT4276BHUFD#PBF4x5 QFN-28H$4.46$3.12
LT4276BHUFD#TRPBF4x5 QFN-28H$4.52$3.18
LT4276BIUFD#PBF4x5 QFN-28I$3.71$2.60
LT4276BIUFD#TRPBF4x5 QFN-28I$3.77$2.66
LT4276CHUFD#PBF4x5 QFN-28H$3.60$2.52
LT4276CHUFD#TRPBF4x5 QFN-28H$3.66$2.58
LT4276CIUFD#PBF4x5 QFN-28I$3.21$2.25
LT4276CIUFD#TRPBF4x5 QFN-28I$3.27$2.31
Demo Boards
Part NumberDescriptionPrice
DC2046A-ALT4276B/LT4321 Demo Board | PoE+ (25W, 3.3V/6.8A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2046A-BLT4276B/LT4321 Demo Board | PoE+ (25W, 5V/4.7A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2046A-CLT4276B/LT4321 Demo Board | PoE+ (25W, 12V/1.9A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2046A-DLT4276B/LT4321 Demo Board | PoE+(25W, 24V/1A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2046A-ELT4276A/LT4321 Demo Board | LTPoE++ (38.7W, 5V/7A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2046A-FLT4276C/LT4321 Demo Board | PoE (13W, 5V/2.3A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2262A-ALT4276A/LT4321 Demo Board | LTPoE++ (70W, 5V/13A) PD with DC/DC and Ideal Diode Bridge$95.00
DC2262A-BLT4276A/LT4321 Demo Board | LTPoE++ (90W, 12V/7A) PD with DC/DC and Ideal Diode Bridge$95.00
Companion Boards
Part NumberDescriptionPrice
DC1814A-ALTC4274A-1 Demo Board | LTPoE++ (38.7W) PSE$100.00
DC1815A-ALTC4266A-1 Demo Board | 4-Port 38.7W LTPoE++ PSE (req. DC590)$200.00
Reliability Data
Product Selector Card
Press Release
Related Product
LT4276 - LTPoE++/PoE+/PoE PD Forward/Flyback Controller
R572 - Reliability Data
LT4321 - PoE Ideal Diode Bridge Controller
PoE PD Controllers
Power over Ethernet Solutions
高效率 LTPoE++ PD 控制器集成了正激式 / 反激式控制器
LT4276 Footprints and Symbols