LT4295 - IEEE 802.3bt PD Interface with Forward/Flyback Controller


  • IEEE 802.3af/at/bt(Draft 2.0) Powered Device (PD) with Forward/Flyback Controller
  • Supports Up to 71 Watt PDs
  • 5-Event Classification Sensing
  • Superior Surge Protection (100V Absolute Maximum)
  • Wide Junction Temperature Range (–40°C to 125°C)
  • >94% End-to-End Efficiency with LT4321 Ideal Bridge
  • External Hot Swap N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency
  • No-Opto Flyback Operation
  • Auxiliary Power Support as Low as 9V
  • Easy Migration of LTPoE++® PDs to IEEE 802.3bt PDs
  • Pin Compatible with LT4276A/B/C
  • 28-Lead 4mm × 5mm QFN Package

Typical Application

LT4295 Typical Application


The LT4295 is an IEEE 802.3af/at/bt(Draft 2.0)-compliant powered device (PD) interface controller with a switching regulator controller. The T2P output indicates the number of classification events received during IEEE 802.3bt-compliant mutual identification and negotiation of available power.

The LT4295 supports both forward and flyback power supply topologies. The flyback topology supports No-Opto feedback. Auxiliary input voltages can be accurately sensed with just a resistor divider connected to the AUX pin.

The LT4295 utilizes an external, low R DS(on) N-channel hot swap MOSFET and supports the LT4320/LT4321 ideal diode bridges, to extend the end-to-end power delivery efficiency and eliminate costly heat sinks.

The LT4295 also includes an on-chip detection signature resistor, thermal protection, slope compensation, and many user configurable settings including classification signature, inrush current, switcher frequency, gate drive delay, soft-start, and load compensation.


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

Part Number Package Code Temp Package
LT4295HUFD#PBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4295HUFD#TRPBF 4x5 QFN-28 UFD H 05-08-1712 Yes
LT4295IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT4295IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes

LT4295 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
LT4295HUFD#PBF 4x5 QFN-28 H $4.71 $3.30 Yes
LT4295HUFD#TRPBF 4x5 QFN-28 H $4.77 $3.36 Yes
LT4295IUFD#PBF 4x5 QFN-28 I $3.93 $2.75 Yes
LT4295IUFD#TRPBF 4x5 QFN-28 I $3.99 $2.81 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
DC2475A-A LT4295/LT4321 Demo Board | PoE++ (40W, 12V/3A) PD with Flyback DC/DC and Ideal Diode Bridge $95.00
DC2476A-A LT4295/LT4321 Demo Board | PoE++ (71W/24V/2.7A or 62W/24V/2.3A) PD with Flyback DC/DC and Ideal Diode Bridge $95.00
DC2539A-A LT4295/LT4321 Demo Board | PoE++ (51W, 12V/3.9A) PD with Flyback DC/DC and Ideal Diode Bridge $95.00
DC2584A-A LT4295/LT4321 Demo Board | PoE++ (71W/12V/5.5A) PD with Forward DC/DC and Ideal Diode Bridge $95.00
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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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Design Tools

Linear Technology provides a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more. Please visit our Design Tools page to view and download:

  • LTspice - A powerful SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators
  • LTpowerCAD - A complete power supply selection, synthesis and design tool
  • LTpowerPlay - A development environment supporting Linear Technology's Digital Power System Management (PSM) products
  • PScope & QuikEval - USB-based product demonstration and data acquisition system for use with our ADCs, DACs, and more
  • Linduino - Arduino compatible system for developing and distributing firmware libraries and example code
  • LinearLab Tools - A collection of Matlab and Python programs that provide direct access to Linear Technology’s data converter evaluation boards
  • And More!

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