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General Description

The MAX8655 evaluation kit (EV kit) is a fully assem-

bled and tested surface-mount PCB that contains

a fixed-frequency, pulse-width modulated (PWM) step-

down switching regulator. The MAX8655 EV kit

provides a 1.2V output voltage from a 10.8V to 13.2V

input source and delivers up to 20A output current.

The MAX8655 IC features internal high-side and low-

side power MOSFETs.

A reference input is provided for use with a high-

accuracy external reference (REFIN) or for DDR and

tracking applications. The MAX8655 EV kit operates at

600kHz. The MAX8655 IC has a programmable internal

oscillator with frequency range from 200kHz to 1MHz.

The MAX8655 can also be synchronized to an external

clock by connecting the clock signal to FSYNC. A syn-

chronization output (SYNCO) is provided to synchro-

nize a second MAX8655 180° out-of-phase with the first

by connecting SYNCO of the first MAX8655 to FSYNC

of the second.

Features

♦ 10.8V to 13.2V Input-Voltage Range

♦ 20A Maximum Output Current (Additional Airflow

or Heat Sink May be Required Above 13A of

Output Current)

♦ Adjustable Output from 0.7V to 5.5V

♦ Internal High-Side and Low-Side Power MOSFETs

♦ 200kHz to 1MHz Adjustable Switching Frequency

and SYNC Input

♦ SYNCO Synchronizes 2nd Regulator 180° Out-of-

Phase

♦ Monotonic Startup Provides Safe Starting Into a

Pre-Biased Output

♦ Enable Input and Power-OK Signals

♦ Low-Profile Components

♦ Lead-Free and RoHS Compliant

♦ Fully Assembled and Tested

Evaluates: MAX8655/MAX8688

MAX8655 Evaluation Kit

________________________________________________________________

Maxim Integrated Products

19-4331; Rev 0; 10/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

PART TYPE

MAX8655EVKIT+ EV Kit

Denotes lead-free and RoHS compliant.

MAX8655 Circuit

Component Lists

DESIGNATION QTY DESCRIPTION

C1 1 N ot i nstal l ed , cer am i c cap aci tor ( 1210)

C2, C3, C4 3

10µF, 25V X5R ceramic capacitors

(1210)

Murata GRM32DR61E106KA12B

C6 1

2.2µF ±20%, 10V X5R ceramic

capacitor (0603)

Murata GRM188R61A225KE34

C6A1, C7A,

C8A

0 Not installed, ceramic capacitors

C7 1

0.22µF, 10V ceramic capacitor (0603)

Murata GRM188R71A224KA01

C8 1

0.22µF, 25V X7R ceramic capacitor

(0603)

Murata GRM188R71E224KA88D

C9–C12 4

100µF, 6.3V X5R ceramic capacitors

(1210)

Murata GRM32ER60J107ME20

DESIGNATION QTY DESCRIPTION

C13, C17 2

0.47µF, 10V X5R ceramic capacitors

(0402)

Murata GRM155R61A474KE15

C14 1

1µF ±20%, 10V X5R ceramic

capacitor (0603)

Murata GRM188R61A105KA61

C15 1

1000pF ±10%, 50V ceramic capacitor

(0603)

Murata GRM188R71H102KA01

C16 1

0.022µF, 50V X5R ceramic capacitor

(0402)

Murata GRM155R71H223KA12D

C18 1

100pF, 50V X7R ceramic capacitor

(0402)

Murata GRM1555C1H101JZ01

C19 1

470pF, 50V ceramic capacitor (0402)

Murata GRM155R71H471KA01

C20, R1 0 N ot i nstal l ed , cer am i c cap aci tor s ( 0402)

Summary of content (14 pages)

PAGE 1
9-4331; Rev 0; 10/08 MAX8655 Evaluation Kit The MAX8655 evaluation kit (EV kit) is a fully assembled and tested surface-mount PCB that contains a fixed-frequency, pulse-width modulated (PWM) stepdown switching regulator. The MAX8655 EV kit provides a 1.2V output voltage from a 10.8V to 13.2V input source and delivers up to 20A output current. The MAX8655 IC features internal high-side and lowside power MOSFETs.
PAGE 2
Evaluates: MAX8655/MAX8688 MAX8655 Evaluation Kit Component Lists (continued) MAX8655 Circuit DESIGNATION QTY DESCRIPTION D1 1 SMD Schottky diode Central Semi CM0SH-3 BK JP1, JP3, JP9 3 Terminal blocks, 5mm On Shore EDZ500/2DS Digi-Key ED1975-ND JP2, JP5, JP6, JP7 4 2-pin headers, 0.1in JP4 1 4-pin header, 0.1in JP8, JP10 L1 R2, R17 2 3-pin headers, 0.1in 1 0.56µH, 1.8mΩ, 27.5A inductor (11.5mm x 10.
PAGE 3
MAX8655 Evaluation Kit Recommended Equipment Before beginning, the following equipment is needed: • MAX8655 EV kit • Up to 12V at 5A adjustable DC power supply • • • Digital multimeters (DMM) Up to 20A load Ammeter (optional) Procedure The EV kit features an FSYNC pad to allow the converter to synchronize with an external clock. See the Evaluating Other Switching Frequencies and External Clock Synchronization (FSYNC and SYNCO) section.
PAGE 4
Evaluates: MAX8655/MAX8688 MAX8655 Evaluation Kit Power-OK (POK) POK is an open-drain output on the MAX8655 that monitors the output voltage. When the output is above 92% of its nominal regulation voltage, POK is high impedance. When the output drops below 89% of its nominal regulation voltage, POK is internally pulled low. POK is also internally pulled low when the MAX8655 is shut down or in a fault condition.
PAGE 5
MAX8655 Evaluation Kit EFFICIENCY vs.
PAGE 6
Figure 1a. MAX8655 EV Kit Schematic (Sheet 1 of 2) _______________________________________________________________________________________ JP10 3 2 1 JP8 3 2 1 JP7 2 1 JP6 2 1 JP5 2 1 GND GND GND GND AVL GND GND R12 100kΩ AVL AVL AVLI VL VIN REFIN 4 JP4 3 2 1 JP2 2 1 JP1 C1 OPEN EN REFIN SYNC GND VIN R7 40.2kΩ GND EN GND C16 0.022μF C8A OPEN GND POK GND GND C8 0.
PAGE 7
JP204 JP203 JP202 JP201 3 2 1 3 2 1 3 2 1 4 3 2 1 SCL SDA SCL SDA EN TP6 V33 R215 10kΩ 5 RST 6 4 2 1 3 C202 100nF FLT- OTP V33 C201 100nF CLKIN TP4 TP2 R204 OPEN SDA RST CLKIN DVDD DGND OTP 22 7 8 9 10 19 2 TP3 RSC 11 AGND AVDD REFO A3 25 13 14 15 16 17 18 R19 100kΩ V33 AGNDP A2 A1 DACOUT 12 1 C203 100nF R217 100Ω RS- RSC 20 SCL NC8 NC9 ENOUT FLT MAX8688 RS+ 21 U201 ISNC ISN+ ISN- 24 23 ISNC ISN- ISIN+ R203 1kΩ A3 V33
PAGE 8
Evaluates: MAX8655/MAX8688 MAX8655 Evaluation Kit Figure 2.
PAGE 9
MAX8655 Evaluation Kit Evaluates: MAX8655/MAX8688 Figure 3.
PAGE 10
Evaluates: MAX8655/MAX8688 MAX8655 Evaluation Kit Figure 4.
PAGE 11
MAX8655 Evaluation Kit Evaluates: MAX8655/MAX8688 Figure 5.
PAGE 12
Evaluates: MAX8655/MAX8688 MAX8655 Evaluation Kit Figure 6.
PAGE 13
MAX8655 Evaluation Kit Evaluates: MAX8655/MAX8688 Figure 7.
PAGE 14
Evaluates: MAX8655/MAX8688 MAX8655 Evaluation Kit Figure 8. MAX8655 EV Kit PCB Layout—Solder Side 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.