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General Description

The MAX8643 evaluation kit (EV kit) is a fully assembled

and tested PCB that demonstrates the capabilities of

the MAX8643 integrated 3A step-down regulator. The

EV kit generates a +1.8V output voltage at load cur-

rents up to 3A from a 2.35V to 3.6V input voltage range.

The MAX8643 switches at 1MHz and up to 95% effi-

ciency with the supplied components.

Features

 Internal 37mΩ On-Resistance MOSFETs

 3A Output PWM Step-Down Regulator

 ±1% Output Accuracy over Load, Line, and

Temperature

 Operates from 2.35V to 3.6V Input Supply

 Adjustable Output from 0.6V to (0.9 x V

)

 500kHz to 2MHz Adjustable Frequency

 Allows All-Ceramic Capacitor Design

 Programmable Soft-Start Time

 24-Pin, 4mm x 4mm Thin QFN Package

 REFIN for DDR Termination and Tracking

Applications

 Surface-Mount Components

 Assembled and Tested

Evaluates: MAX8643

MAX8643 Evaluation Kit

________________________________________________________________

Maxim Integrated Products

19-0642; Rev 0; 10/06

Component List

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

PART TEMP RANGE IC PACKAGE

MAX8643EVKIT+ 0°C to +70°C 24 TQFN (4mm x 4mm)

DESIGNATION QTY DESCRIPTION

C1, C2 2

22µF ±10%, 6.3V X5R ceramic

capacitors (0805)

TDK C2012X5R0J226K

C3, C9 2

0.1µF ±10%, 25V X7R ceramic

capacitors (0603)

TDK C1608X7R1E104K

C4, C6 2

0.01µF ±10%, 50V X7R ceramic

capacitors (0603)

TDK C1608X7R1H103K

C5 1

1µF ±10%, 16V X5R ceramic

capacitor (0603)

TDK C1608X5R1C105K

C7, C13, C14 0

Not installed, ceramic capacitors

(0603)

C8 1

0.022µF ±10%, 50V X7R ceramic

capacitor (0603)

TDK C1608X7R1H223K

C10 1

560pF ±10%, 50V X7R ceramic

capacitor (0603)

TDK C1608X7R1H561K

C11 1

1500pF ±10%, 50V X7R ceramic

capacitor (0603)

TDK C1608X7R1H152K

C12 1

33pF ±5pF, 50V C0G ceramic

capacitor (0603)

TDK C1608C0G1H330CT

C15 1

1000pF ±10%, 50V X7R ceramic

capacitor (0603)

TDK C1608X7R1H102K

Component List continued on next page.

Quick Start

Recommended Equipment

• 2V to 4V at +3A variable DC power supply or battery

• Digital multimeter (DMM)

• Up to 3A load

• Ammeter (optional)

Procedure

The MAX8643 EV kit is fully assembled and tested.

Follow the steps below to verify board operation.

1) Preset the DC power supply to 3.3V. Turn off the

power supply. Caution: Do not turn on the power

supply until all connections are made.

2) Remove the shunt from JU1.

3) Verify that no two pins are shunted together on

jumper JU3.

Denotes a lead-free and RoHS-compliant EV kit.

Summary of content (6 pages)

PAGE 1
9-0642; Rev 0; 10/06 MAX8643 Evaluation Kit The MAX8643 evaluation kit (EV kit) is a fully assembled and tested PCB that demonstrates the capabilities of the MAX8643 integrated 3A step-down regulator. The EV kit generates a +1.8V output voltage at load currents up to 3A from a 2.35V to 3.6V input voltage range. The MAX8643 switches at 1MHz and up to 95% efficiency with the supplied components.
PAGE 2
MAX8643 Evaluation Kit Evaluates: MAX8643 Component List (continued) DESCRIPTION 4) Verify that there is a shunt on pins 1-2 of jumper JU4. DESIGNATION QTY JU1, JU2 2 2-pin headers JU3, JU4 2 3-pin headers 5) Connect the positive lead of the power supply to the IN pad and connect the negative lead of the power supply to the GND pad on the EV kit. L1 1 0.47µH, 7.6mΩ, 9.6A inductor (7.
PAGE 3
MAX8643 Evaluation Kit L VOUT Evaluates: MAX8643 L LX VOUT LX C2 C2 MAX8643 R6 MAX8643 R6 OUT OUT R8 8.06kΩ C10 C10 Ri 8kΩ CTL1 CTL2 FB R4 C11 COMP VOLTAGE SELECT FB CTL2 R9 C12 1a CTL1 R4 C11 COMP 1b C12 Figure 1. Preset and Adjustable Output Configuration When externally programming the MAX8643 (Figure 1a), install an 8.06kΩ resistor at R8. The output voltage is then determined by: R9 = 4836 VOUT − 0.6 For an output voltage of 0.6V, install an 8.
PAGE 4
Evaluates: MAX8643 MAX8643 Evaluation Kit BST IN 23 C13 OPEN C1 22µF C3 0.1µF R1 10Ω 22 21 VDD 2 C5 1µF IN 16 IN LX LX 15 IN LX 24 EN PGND FB U1 C6 0.01µF 3 REFIN CTL1 VDD 4 PWRGD CTL2 C15 1000pF OUT R6 158Ω 1% C10 560pF 17 9 R4 C11 2.67kΩ 1500pF 1% COMP 1 JU4 2 3 R10 2.2Ω L1 0.47µH 14 MAX8643 VDD 1 JU3 2 3 C9 0.1µF 10 OUT 20 PGND 19 PGND 18 PGND VDD R2 10kΩ JU1 13 8 R8 OPEN R5 20kΩ R9 OPEN VDD PWRGD R3 1kΩ 5 FREQ R7 49.9kΩ 1% JU2 6 C8 0.
PAGE 5
MAX8643 Evaluation Kit Evaluates: MAX8643 Figure 3. MAX8643 EV Kit Component Placement Guide—Top Silkscreen Figure 4. MAX8643 EV Kit PCB Layout—Component Side Figure 5.
PAGE 6
Evaluates: MAX8643 MAX8643 Evaluation Kit Figure 6. MAX8643 EV Kit PCB Layout—Layer 3 Figure 7. MAX8643 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.