LT4275 - LTPoE++/PoE+/PoE PD Controller


  • IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller
  • LTPoE++ Supports Power Levels Up to 90W
  • LT4275A 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
  • LT4275B is IEEE 802.3at/af Compliant
  • LT4275C is IEEE 802.3af Compliant
  • 100V Absolute Maximum Input Voltage
  • Wide Junction Temperature Range (–40°C to 125°C)
  • Overtemperature Protection
  • Integrated Signature Resistor
  • External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency
  • Programmable Aux Power Support as Low as 9V
  • Optional Support of Non-Standard Low Voltage PoE
  • Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

Typical Application

LT4275 Typical Application


The LT®4275 is a pin-for-pin compatible family of IEEE 802.3 and LTPoE++ powered device (PD) controllers.

The LT4275A employs a proprietary LTPoE++ classification scheme, delivering 38.7W, 52.7W, 70W or 90W of power at the PD RJ45 connector. The LT4275A is fully compatible with IEEE 802.3. The LT4275B is an IEEE 802.3at compliant, Type 2 (PoE+) PD delivering up to 25.5W. The LT4275C is an IEEE 802.3af compliant, Type 1 (PoE) PD delivering up to 13W.

The LT4275 internal charge pump provides an N-channel MOSFET solution, eliminating a larger and more costly P-channel MOSFET. A low RDS(ON) MOSFET also maximizes power delivery and efficiency, reduces power and heat dissipation, and eases thermal design. Startup inrush current is adjustable with an external capacitor. The LT4275 also includes a power good output, on-board signature resistor, undervoltage lockout, and thermal protection. The LT4275A/LT4275B drives a single opto-coupler to indicate the power level of the attached PSE. Pin-selectable support for non-standard low voltage operation is provided. Auxiliary power override is supported with the AUX pin.

The LT4275A can be configured to support all possible LTPoE++, 802.3at and 802.3af power levels with external component changes.


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

Part Number Package Code Temp Package
LT4275AHDD#PBF 3x3 DFN-10 DD H 05-08-1699 RoHS
LT4275AHDD#TRPBF 3x3 DFN-10 DD H 05-08-1699 RoHS
LT4275AHMS#PBF MS-10 MS H 05-08-1661 RoHS
LT4275AHMS#TRPBF MS-10 MS H 05-08-1661 RoHS
LT4275AIDD#PBF 3x3 DFN-10 DD I 05-08-1699 RoHS
LT4275AIDD#TRPBF 3x3 DFN-10 DD I 05-08-1699 RoHS
LT4275AIMS#PBF MS-10 MS I 05-08-1661 RoHS
LT4275AIMS#TRPBF MS-10 MS I 05-08-1661 RoHS
LT4275BHDD#PBF 3x3 DFN-10 DD H 05-08-1699 RoHS
LT4275BHDD#TRPBF 3x3 DFN-10 DD H 05-08-1699 RoHS
LT4275BHMS#PBF MS-10 MS H 05-08-1661 RoHS
LT4275BHMS#TRPBF MS-10 MS H 05-08-1661 RoHS
LT4275BIDD#PBF 3x3 DFN-10 DD I 05-08-1699 RoHS
LT4275BIDD#TRPBF 3x3 DFN-10 DD I 05-08-1699 RoHS
LT4275BIMS#PBF MS-10 MS I 05-08-1661 RoHS
LT4275BIMS#TRPBF MS-10 MS I 05-08-1661 RoHS
LT4275CHDD#PBF 3x3 DFN-10 DD H 05-08-1699 RoHS
LT4275CHDD#TRPBF 3x3 DFN-10 DD H 05-08-1699 RoHS
LT4275CHMS#PBF MS-10 MS H 05-08-1661 RoHS
LT4275CHMS#TRPBF MS-10 MS H 05-08-1661 RoHS
LT4275CIDD#PBF 3x3 DFN-10 DD I 05-08-1699 RoHS
LT4275CIDD#TRPBF 3x3 DFN-10 DD I 05-08-1699 RoHS
LT4275CIMS#PBF MS-10 MS I 05-08-1661 RoHS
LT4275CIMS#TRPBF MS-10 MS I 05-08-1661 RoHS

LT4275 Package Drawing
LT4275 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Temp Price
LT4275AHDD#PBF 3x3 DFN-10 H $3.86 $2.70 View
LT4275AHDD#TRPBF 3x3 DFN-10 H $2.76 View
LT4275AHMS#PBF MS-10 H $3.86 $2.70 View
LT4275AHMS#TRPBF MS-10 H $2.76 View
LT4275AIDD#PBF 3x3 DFN-10 I $3.21 $2.25 View
LT4275AIDD#TRPBF 3x3 DFN-10 I $2.31 View
LT4275AIMS#PBF MS-10 I $3.21 $2.25 View
LT4275AIMS#TRPBF MS-10 I $2.31 View
LT4275BHDD#PBF 3x3 DFN-10 H $3.09 $2.16 View
LT4275BHDD#TRPBF 3x3 DFN-10 H $2.22 View
LT4275BHMS#PBF MS-10 H $3.09 $2.16 View
LT4275BHMS#TRPBF MS-10 H $2.22 View
LT4275BIDD#PBF 3x3 DFN-10 I $2.57 $1.80 View
LT4275BIDD#TRPBF 3x3 DFN-10 I $1.86 View
LT4275BIMS#PBF MS-10 I $2.57 $1.80 View
LT4275BIMS#TRPBF MS-10 I $1.86 View
LT4275CHDD#PBF 3x3 DFN-10 H $2.49 $1.74 View
LT4275CHDD#TRPBF 3x3 DFN-10 H $1.80 View
LT4275CHMS#PBF MS-10 H $2.49 $1.74 View
LT4275CHMS#TRPBF MS-10 H $1.80 View
LT4275CIDD#PBF 3x3 DFN-10 I $2.07 $1.45 View
LT4275CIDD#TRPBF 3x3 DFN-10 I $1.51 View
LT4275CIMS#PBF MS-10 I $2.07 $1.45 View
LT4275CIMS#TRPBF MS-10 I $1.51 View
Buy NowRequest Samples
* 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
DC2093A-A LT4275A/LT4321 LTPoE++/PoE+/PoE PD Demo Board $95.00
DC2093A-B LT4275B/LT4321 PoE+/PoE PD Demo Board $95.00
DC2093A-C LT4275C/LT4321 PoE PD Demo Board $95.00
DC2125A LT4275/LT4321/LTM8027 Demo Board | LTPoE++ PD Plus Diode Bridge & DC/DC Controller $125.00
Buy Now

Companion Boards

Part Number Description Price Documentation
DC1814A-A LTC4274A-1 Demo Board | LTPoE++ (38.7W) PSE $100.00
DC1814A-B LTC4274A-2 Demo Board | LTPoE++ (52.7W) PSE $100.00
DC1814A-C LTC4274A-3 Demo Board | LTPoE++ (70W) PSE $100.00
DC1814A-D LTC4274A-4 Demo Board | LTPoE++ (90W) PSE $100.00
DC1815A-A LTC4266A-1 Demo Board | 4-Port 38.7W LTPoE++ PSE (req. DC590) $200.00
DC1815A-B LTC4266A-2 Demo Board | 4-Port 52.7W LTPoE++ PSE (req. DC590) $200.00
DC1815A-C LTC4266A-3 Demo Board | 4-Port 70W LTPoE++ PSE (req. DC590) $200.00
DC1815A-D LTC4266A-4 Demo Board | 4-Port 90W LTPoE++ PSE (req. DC590) $200.00
Buy Now
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 Industrial Applications

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email with questions and comments.

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:

Technical Support