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Datasheet Linear Technology LTC4257CS8#TRPBF

ManufacturerLinear Technology
SeriesLTC4257
Part NumberLTC4257CS8#TRPBF

IEEE 802.3af PD Power over Ethernet Interface Controller

Datasheets

  • Download » Datasheet PDF, 270 Kb, Revision: B, File uploaded: Oct 25, 2017
    LTC4257 - IEEE 802.3af PD Power over Ethernet Interface Controller
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    LTC4257
    IEEE 802.3af PD
    Power over Ethernet
    Interface Controller U FEATURES
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    в–  DESCRIPTIO Complete Power Interface Port for IEEE 802.3afВ®
    Powered Devices (PDs)
    Onboard 100V, 400mA Power MOSFET
    Precision Input Current Limit
    Onboard 25k Signature Resistor
    Programmable Classification Current (Class 0-4)
    Undervoltage Lockout
    Smart Thermal Protection
    Power Good Signal
    Available in 8-Pin SO and Low Profile (3mm Г— 3mm)
    DFN Packages U ...

Prices

Packaging

PackageSO-8
Package CodeS8
Package Index05-08-1610 (S8)

Parametrics

Number of Channels1
Design ToolsLTspice Model
Export Controlno
I2C Interfaceno
IEEE-Compliant ClassificationOne Event
IEEE-Compliant DetectionYes (Internal 25k resistor)
IEEE-Compliant DisconnectionN/A
Max Power13 W
Operating Temperature Range0 to 70 °C
PSE/PDPD
PoE Type1

Eco Plan

RoHSCompliant

Design Notes

  • Download » Design Notes - DN338 PDF, 80 Kb, File published: May 2, 2004
    Power over Ethernet Isolated Power Supply Delivers 11.5W at 90% Efficiency
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    Power over Ethernet Isolated Power Supply
    Delivers 11.5W at 90% Efficiency – Design Note 338
    Jesus Rosales
    fewer switches to turn on and off the better. A push-pull
    converter could be used, but the additional complexity
    is not justified at this power level. A single transistor
    forward converter is another option, but requires
    an additional output inductor and rectifier. A flyback
    converter is the simplest choice. Flyback converters
    are thought to be less efficient than forward and pushpull converters, but that changes when the output is
    synchronously rectified (a MOSFET is used instead of
    a diode to rectify the output). When powering IP telephones, wireless access points,
    PDA charging stations and other PDs (Powered Devices)
    from an Ethernet cable, designers have at most 12.95W
    of available power per the IEEE 802.3af standard. Increased demands for power mandate a very efficient
    power converter especially for classВ 3 devices (consuming between 6.49W and 12.95W). The more power lost
    in the converter, the less power available for the PD.
    The voltage available from the PSE (Power Sourcing
    Equipment) ranges from 44V to 57V, but PDs need to
    operate with as much as 20О© of series wire resistance.
    A PD can never draw more than 350mA or 12.95W
    continuously. With the maximum input current of
    350mARMS, the input voltage can droop as much as ...

Moldel Line

Series: LTC4257 (8)

Manufacturer's Classification

  • Monitor, Control and Protection > Power-over-Ethernet (PoE) Interface Controllers > PoE Powered Device (PD)

Other Names:

LTC4257CS8TRPBF, LTC4257CS8 TRPBF

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