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MAX5974A Evaluation Kit

Evaluates: MAX5974A

General Description

The MAX5974A evaluation kit (EV kit) is a fully assembled

and tested surface-mount circuit board featuring the

MAX5974A active-clamped, spread-spectrum, current-

mode PWM controller for Power-over-Ethernet (PoE)

powered device (PD) applications. The EV kit is a

compact and low-cost design used in Power-over-

LAN (PoLAN) applications requiring DC power from

an Ethernet network port for PDs such as IP phones,

wireless access nodes, and security cameras.

The EV kit features a galvanically isolated 25W, 600kHz

switching frequency forward DC-DC converter using

the IC. The circuit achieves high efficiency up to 92%

(VIN = +42V) using a coupled-inductor forward DC-DC

converter topology. The surface-mount transformer

provides up to +1650V galvanic isolation for the output.

The EV kit output voltage is configured for +5V and

provides up to 4.7A load current.

The EV kit includes the MAX5969B IEEE

802.3af/

at-compliant network PD interface-controller IC, which

provides PD detection signature, PD classification

signature, in-rush current control, and undervoltage

lockout (UVLO).

The EV kit circuit receives its power from IEEE 802.3af/

at-compliant power-sourcing equipment (PSE). The PSE

provides the required -30V to -57V DC power over an

unshielded twisted-pair Ethernet network cable to the

EV kit’s RJ45 MagJack

. The EV kit features a 1 x 1Gb

RJ45 MagJack and two full-bridge diodes for separating

the DC power provided by an endspan or midspan

Ethernet system.

The EV kit circuit can also be powered by a +37V to

+57V wall-adapter power source applied at the PWR+

and PWR- PCB pads. When a wall-adapter power source

is detected, it takes precedence over the PSE source,

allowing the wall adapter to power the EV kit.

Warning: The EV kit is designed to operate with high

voltages. Dangerous voltages are present on this EV kit

and on equipment connected to it. Users who power up

this EV kit or power the sources connected to it must be

careful to follow safety procedures appropriately to work

with high-voltage electrical equipment.

Under severe fault or failure conditions, this EV kit may

dissipate large amounts of power that could result in the

mechanical ejection of a component or of component

debris at high velocity. Operate this kit with care to avoid

possible personal injury.

Features

S IEEE 802.3af/at-Compliant PD Interface Circuit

S -30V to -57V Input Range

S Demonstrates an Isolated 23.5W Coupled-Inductor

Forward DC-DC Converter

S 92% Efficiency (MAX5974A DC-DC Circuitry)

S Isolated +5V Output at 4.7A

S PD Detection and Configurable Classification

Signatures

S 2-Event Classification or Wall-Adapter Detect

Output

S In-Rush Current Limit of 180mA (max)

S Internal UVLO at +16V

S Evaluates Endspan and Midspan Ethernet

Systems

S Simplified Wall-Adapter Interface

S Proven PCB Layout

S Fully Assembled and Tested

Ordering Information

19-5880; Rev 0; 5/11

#Denotes RoHS compliant.

IEEE is a registered service mark of the Institute of Electrical

and Electronics Engineers, Inc.

MagJack is a registered trademark of Bel Fuse Inc.

PART TYPE

MAX5974AEVKIT# EV Kit

Summary of content (11 pages)

PAGE 1
9-5880; Rev 0; 5/11 MAX5974A Evaluation Kit The EV kit features a galvanically isolated 25W, 600kHz switching frequency forward DC-DC converter using the IC. The circuit achieves high efficiency up to 92% (VIN = +42V) using a coupled-inductor forward DC-DC converter topology. The surface-mount transformer provides up to +1650V galvanic isolation for the output. The EV kit output voltage is configured for +5V and provides up to 4.7A load current. The EV kit includes the MAX5969B IEEE® 802.
PAGE 2
Evaluates: MAX5974A MAX5974A Evaluation Kit Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION C1 1 10pF Q5%, 50V COG ceramic capacitor (0603) Murata GRM1885C1H100H C2 1 0.1µF Q10%, 100V X7R ceramic capacitor (1206) KEMET C1206C104K1RACTU C22 1 1000pF Q10%, 1500V X7R ceramic capacitor (1210) AVX LD10SC102KAB1A C3 1 0.
PAGE 3
MAX5974A Evaluation Kit DESIGNATION QTY DESCRIPTION R7, R26 2 499I Q1% resistors (0402) R9, R27 2 100kI Q1% resistors (0402) R10 1 2kI Q1% resistor (0402) DESIGNATION QTY DESCRIPTION R50 1 10I Q1% resistor (1206) RJ45 1 RJ45 MagJack 1G-Ethernet, 802.3af/at standard Bel Fuse Inc.
PAGE 4
Evaluates: MAX5974A MAX5974A Evaluation Kit Quick Start • MAX5974A EV kit Required Equipment • IEEE 802.3af/at-compliant PSE and Category 5e Ethernet network cable • -48V, 1A-capable DC power supply • Voltmeter Hardware Connections The EV kit is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on the power supply until all connections are completed.
PAGE 5
MAX5974A Evaluation Kit Wall-Adapter Power Source (PWR+, PWR-) The EV kit can also accept power from a wall-adapter DC power source applied at the PWR+ and PWR- PCB pads. The wall-adapter power-source operating-voltage range must be within +37V to +57V for the EV kit. When the wall-adapter power source is above +30V, it takes precedence over the PSE source. Once the walladapter power source is detected, the MAX5969B’s internal isolation switch disconnects VSS from RTN.
PAGE 6
LOAD REGULATION vs. OUTPUT CURRENT EFFICIENCY vs. OUTPUT CURRENT 100 1.5 90 VIN = +48V 70 60 1.0 VIN = +57V LOAD REGULATION (%) 80 EFFICIENCY (%) Evaluates: MAX5974A MAX5974A Evaluation Kit VIN = +42V 50 40 30 VIN = +42V VIN = +48V 0.5 0 -0.5 VIN = +57V 20 -1.0 10 0 0 1 2 3 4 -1.5 5 0 OUTPUT CURRENT (A) 1 2 3 4 5 OUTPUT CURRENT (A) Figure 1. MAX5974A EV Kit Efficiency vs. Output (VIN = +42V, +48V, and +57V) Figure 2. MAX5974A EV Kit Load Regulation vs.
PAGE 7
MAX5974A Evaluation Kit Evaluates: MAX5974A Figure 4.
PAGE 8
Evaluates: MAX5974A MAX5974A Evaluation Kit 1.0” Figure 5. MAX5974A EV Kit Component Placement Guide—Component Side 1.0” Figure 6.
PAGE 9
MAX5974A Evaluation Kit Figure 7. MAX5974A EV Kit PCB Layout—GND Layer 2 1.0” Figure 8. MAX5974A EV Kit PCB Layout—Signal Layer 3 _______________________________________________________________________________________ 9 Evaluates: MAX5974A 1.
PAGE 10
Evaluates: MAX5974A MAX5974A Evaluation Kit 1.0” Figure 9. MAX5974A EV Kit PCB Layout—Solder Side 1.0” Figure10.
PAGE 11
MAX5974A Evaluation Kit REVISION NUMBER REVISION DATE 0 5/11 DESCRIPTION Initial release PAGES CHANGED — Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.