LM5070

Integrated Power Over Ethernet PD Interface and PWM

Controller

General Description

The LM5070 power interface port and pulse width modula-

tion (PWM) controller provides a complete integrated solu-

tion for Powered Devices (PD) that connect into Power over

Ethernet (PoE) systems. The LM5070 integrates an 80V,

400mA line connection switch and associated control for a

fully IEEE 802.3af compliant interface with a full featured

current mode pulse width modulator dc-dc converter. All

power sequencing requirements between the controller in-

terface and switch mode power supply (SMPS) are inte-

grated into the IC. Two options are available providing either

an 80% maximum duty cycle limit with slope compensation

(on the –80 suffix) device or a 50% maximum duty cycle limit

and no slope compensation on the (–50 suffix) device.

Features

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Fully Compliant 802.3af Power Interface Port

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80V, 1

Ω, 400 mA Internal MOSFET

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Programmable Inrush Current Limit

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Detection Resistor Disconnect Function

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Programmable Classification Current

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Programmable Under-voltage Lockout with

Programmable Hysteresis

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Thermal Shutdown Protection

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Current Mode Pulse Width Modulator

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Supports both Isolated and Non-Isolated Applications

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Error Amplifier and Reference for Non-Isolated

Applications

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Programmable Oscillator Frequency

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Programmable Soft-start

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80% Maximum Duty Cycle Limiter, Slope Compensation

(-80 device)

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50% Maximum Duty Cycle Limiter, No Slope

Compensation (-50 device)

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800 mA Peak Gate Driver

Packages

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TSSOP-16

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LLP-16 (5 mmx5mm)

20120001

December 2004

© 2004 National Semiconductor Corporation

DS201200

www.national.com