LM5071 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Power Over Ethernet PD Controller with Auxiliary Power Power Over Ethernet PD Controller with Auxiliary Power

November 2005
LM5071
Power Over Ethernet PD Controller with Auxiliary Power
Interface
General Description
The LM5071 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 LM5071 is specifically de-
signed for the PD that must accept power from auxiliary
sources such as ac adapters. The auxiliary power inter-
face of the LM5071 activates the PWM controller when the
ac adapter is connected to power the PD when PoE network
power is unavailable. The LM5071 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.
Features
n Compatible with 12V ac adapters
n Fully Compliant 802.3af Power Interface Port
n 80V, 1Ω, 400 mA Internal MOSFET
n Detection Resistor Disconnect Function
n Programmable Classification Current
n Programmable Under-voltage Lockout with
Programmable Hysteresis
n Thermal Shutdown Protection
n Auxiliary Power Enable Pin
n Current Mode Pulse Width Modulator
n Supports both Isolated and Non-Isolated Applications
n Error Amplifier and Reference for Non-Isolated
Applications
n Programmable Oscillator Frequency
n Programmable Soft-start
n 80% Maximum Duty Cycle Limiter, Slope Compensation
(-80 device)
n 50% Maximum Duty Cycle Limiter, No Slope
Compensation (-50 device)
Packages
n TSSOP-16
Block Diagram
© 2005 National Semiconductor Corporation DS201684
20168401
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