Features

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36V ~ 57V input voltage

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Compact and flexible

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Minimal external components

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Robust operation in adverse environments

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12.5W output capacity

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±3% output accuracy

Applications

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Lighting

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IP cameras

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Sensors

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Non-isolated Ethernet equipment

Introduction

Power over Ethernet (PoE) provides power to Ethernet connected devices, through

Ethernet lines, eliminating the need for connecting AC mains to the target devices. In

addition to reducing cabling, PoE provides multiple advantages for many applications

such as LED lighting, cameras, sensors, and additional equipment. These advantages

include network management of devices, power measurement, and elimination of

AC/DC circuitry.

Many PoE applications are isolated, to protect both people and systems from voltage

and current transients. However, many applications do not require isolation, such as

LED lighting and other equipment that is generally out of range for human touch. In

these cases, eliminating the isolation circuitry further reduces cost and power

dissipation at the PoE point of load. MAXREFDES98# is a unique PoE module

reference design, providing 5V at 2.5A (12.5W) from a 36V to 57V input. This design

can be used for evaluation, design, prototyping, and production.

MAXREFDES98# System Board

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MAXREFDES98# includes two function blocks: the PD controller block and the step

down DC-DC power supply block. The PD controller uses the MAX5969A. The

integrated power MOSFET. The DC-DC power supply uses the MAX17503. The

MAX17503 is a 4.5V~60V input, 2.5A output, high-efficiency synchronous step down

converter with internal compensation. The entire design delivers a peak efficiency of

86% with an input of 48V.