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reference designLT4276B

Analog Devices LT4276B

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

Overview

TopologyFlyback Converter
Input voltage37-57 V
Switching frequency200-223 kHz
Output 15 V / 7 A

Description

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.

Features

  • 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 applications

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

More information

Products

Order Code
Data­sheet
Simu­lation
Downloads
Status
Product series
Winding Style
Number of windings
L1(µH)
Zmax(Ω)
IR(mA)
RDC max.(Ω)
VR(V)
Version
VIN
VOut1(V)
IOut1(A)
L(µH)
n
VT(V (AC))
Size
Vaux(V)
RDC 1(Ω)
RDC 2(Ω)
RDC 3(Ω)
Mount
SamplesAvailability & Sample
744272102
SPECWE-SL5 SMT Common Mode Line Filter, sectional, 2
Simu­lation
Availability
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Downloads9 files

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Status Activei| Production is active. Expected lifetime: >10 years.
Product seriesWE-SL5 SMT Common Mode Line Filter
Winding Stylesectional 
Number of windings2 
Inductance [1]1000 µH
Maximum Impedance3600 Ω
Rated Current950 mA
DC Resistance [1]0.18 Ω
Rated Voltage80 V
VersionSMT 
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Inductance1000 µH
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Insulation Test Voltage1000 V (AC)
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MountSMT 
–Check availability
750314783
SPECWE-PoE+ Power over Ethernet Plus Transformer, –, –
Simu­lation
Availability
–
Downloads9 files

EDA models: Components ZIP

CAD files ZIP

Electric models ZIP

Others ZIP

Download all 9 files as zip archive
ZIP

Status Activei| Production is active. Expected lifetime: >10 years.
Product seriesWE-PoE+ Power over Ethernet Plus Transformer
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VersionFlyback 
Input Voltage 48 - 57 V (DC)
Output Voltage 15 V
Output Current 17 A
Inductance26 µH
Turns Ratio4.5:1:2.5 
Insulation Test Voltage2400 V (AC)
SizeEP13 
Auxiliary Voltage12 V
DC Resistance 10.094 Ω
DC Resistance 20.007 Ω
DC Resistance 30.233 Ω
MountSMT 
–Check availability