MAX5971B

Single-Port, 40W, IEEE 802.3af/at, PSE Controller with I²C

40W, I²C, Single-Port, IEEE 802.3af/at-Compliant PSE Controller with Integrated 0.5Ω Power MOSFET and Sense Resistor

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Overview

Features and Benefits
Product Details

Features and Benefits

IEEE 802.3af/at Compliant
Up to 40W for Single-Port PSE Applications
Integrated Power MOSFET and Sense Resistor
Supports 54V Single-Supply Operation
PD Detection and Classification
I²C-Compatible, 2-Wire Serial Interface
Instantaneous Readout of Port Current Through I²C Interface
Programmable Current Limit for Class 5 PDs
High-Capacitance Detection for Legacy Devices
Supports Both DC and AC Load Removal Detections
Current Foldback and Duty-Cycle-Controlled Current Limit
LED Indicator for Port Status
Direct Fast-Shutdown Control Capability
Space-Saving, 28-Pin TQFN (5mm x 5mm) Power Package

Product Details

The MAX5971B is a single-port power controller designed for use in IEEE^® 802.3af/at-compliant power-sourcing equipment (PSE). This device provides powered device (PD) discovery, classification, current limit, and DC and AC load-disconnect detections. The MAX5971B supports both fully automatic operation and software programmability, and features an integrated power MOSFET and sense resistor. The device supports detection and classification operation from a single 54V supply. In addition, it supports 2-event classification and new Class 5 classification of high-power PDs. The MAX5971B provides up to 40W to a single port (Class 5 enabled) and still provides high-capacitance detection for legacy PDs.

The device provides four operating modes to suit different system requirements. By default, auto mode allows the device to operate automatically at its default settings without any software. Semi-automatic mode automatically detects and classifies a device connected to the port after initial software activation, but does not power the port until instructed to by software. Manual mode allows total software control of the device and is useful for system diagnostics. Shutdown mode terminates all port activities and securely turns off power to the port.

The IC features an I²C-compatible, 2-wire serial interface, and is fully software-configurable and programmable. The device provides instantaneous readout of port current through the I²C interface. The device’s extensive programmability enhances system flexibility, enables field diagnosis and allows for uses in other, non-standard applications.

The device provides input undervoltage lockout (UVLO), input undervoltage detection, input overvoltage lockout, overtemperature protection, output voltage slew-rate limit during startup, and LED status indication. The MAX5971B programmability includes startup timeout, overcurrent timeout, and load-disconnect detection timeout.

The device is available in a space-saving, 28-pin TQFN (5mm x 5mm) power package and is rated for the extended (-40°C to +85°C) temperature range.

Applications

Single-Port PSE End-Point Applications
Single-Port PSE Power Injectors (Midspan Applications)
Switches/Routers

Product Categories

Power Monitor, Control, and Protection
- PoE Power Sourcing Equipment (PSE)

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Product Lifecycle Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

MAX5971BEVKIT

Evaluation Kit for the MAX5971B

MAX5971BEVKIT

View Detailed Evaluation Kit Information

The MAX5971B evaluation kit (EV kit) is a fully assembled and tested surface-mount PCB featuring an Ethernet single-port power-sourcing equipment (PSE) circuit for -54V supply rail systems. The IEEE® 802.3af/at-compliant MAX5971B PSE controller IC, in a 28-pin TQFN package, features an internal n-channel power MOSFET forming the main PSE circuit on the EV kit. The IC is used in single-port power-over-Ethernet (PoE) applications.

The EV kit provides optical isolation for the IC's I²C-compatible 2-wire interface. The isolated interface can connect to a PC's USB port through an on-board USB interface circuit. The EV kit can be reconfigured for interfacing to a user's stand-alone microcontroller for isolated or nonisolated operation. In stand-alone operation, the user must supply a separate +3.3V power supply capable of supplying 35mA. The EV kit requires a -32V to -60V power supply (-54V supply rail) capable of supplying 1A or more to the EV kit for powering the powered device (PD) through the 10/100/1000BASE-TX Ethernet network port. The EV kit demonstrates PD discovery, classification, current-limit control, and other functions of an IEEE 802.3af/at-compliant PSE.

The IC controls the -54V DC power to the Ethernet network port by sensing current through the port and controlling the IC's internal power MOSFET. Current is fed to a 1Gb x 1Gb MagJack® module Ethernet output port.

The EV kit demonstrates the full functionality of the IC, such as configurable operational modes, port current information through the I²C interface, high-power modes (programmable up to 40W), PD detection (including legacy PD detection), PD classification, overcurrent protection, current foldback, undervoltage/overvoltage protection, and AC-/DC-disconnect monitoring. All these features are configurable on the EV kit, with additional test points for voltage probing and current measurements provided. The EV kit can also be configured for midspan or end-point network operation. The EV kit software is Windows® 2000, Windows XP®, and Windows Vista® compatible, providing a user-friendly interface to demonstrate the IC features while providing access to each register at the bit level. The program is menu driven, offers a graphical user interface (GUI) with control buttons, and includes a macro engine for automated evaluation and testing of the IC at the system level. The program's macro output files can be automatically saved.

Order the EV kit for a complete PC-based evaluation of the IC. To evaluate the MAX5971A IC, order the MAX5971A EV kit.

Applications

Single-Port PSE End-Point Applications
Single-Port PSE Power Injectors (Midspan Applications)
Switches/Routers

Features & Benefits

IEEE 802.3af/at-Compliant PSE Circuit
Port Current Read-Out Through I²C Interface
High-Power Class 5 Mode Configurable Up to 40W
-32V to -60V Input Voltage Providing 1A
Ethernet Network Ports
- RJ45 10/100/1000BASE-TX Ethernet Network Data Input Port
- RJ45 10/100/1000BASE-TX Ethernet Network PSE Output Port
Demonstrates MAX5971B Internal Power Switch and Current Sensing
Demonstrates Standard and Legacy PD Detection and Classification
Configurable for Midspan or End-Point Mode
Configurable AC/DC Load-Removal Detection and Disconnect Monitoring
Convenient Voltage and Current Test Points
Demonstrates IC's Output-Port LED Status Indicators
Optically Isolated I²C-Compatible 2-Wire PC Interface
Reconfigurable for Stand-Alone Operation or with an External Microcontroller (Requires +3.3V, 35mA Supply)
Windows 2000-, Windows XP-, and Windows Vista (32-Bit)-Compatible Software
Proven PCB Layout
Fully Assembled and Tested

Documentation & Resources

Data Sheets

MAX5971B: Single-Port, 40W, IEEE 802.3af/at, PSE Controller with I²C Data Sheet (Rev. 3)
4/4/2016

PDF

1M

Design Notes

PoE Power Injector
6/17/2015

Tools & Simulations

Software Development

MAX5971B EV Kit Software, 1.0.0

ZIP

Reference Designs (1)

MAXREFDES1015

Minimum Component PSE Controller for Detecting IEEE 802.3af/at Devices

MAXREFDES1015

Minimum Component PSE Controller for Detecting IEEE 802.3af/at Devices

MAXREFDES1015

Minimum Component PSE Controller for Detecting IEEE 802.3af/at Devices

View Detailed Reference Design Information

Features & Benefits

IEEE 802.3af/at Compliant
Up to 40W for Single-Port PSE Applications
Integrated Power MOSFET and Sense Resistor
Supports 54V Single-Supply Operation
PD Detection and Classification
Supports Both AC Load and DC Load Detections
LED Indicator for Port Status

Parts Used

MAX5971B

Resources

Product Recommendations

MAX5971B Companion Parts

Recommended Related Parts

MAX5969B, MAX5969A.

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.