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General Description

The MAX1820/MAX1821 low-dropout, pulse-width-mod-

ulated (PWM) DC-DC buck regulators are optimized to

provide power to the power amplifier (PA) in WCDMA

cell phones; however, they may be applied in many

other applications where high efficiency is a priority. The

supply voltage range is from 2.6V to 5.5V, and the guar-

anteed output current is 600mA; 1MHz PWM switching

allows for small external components, while skip mode

reduces quiescent current to 180µA with light loads.

The MAX1820 is dynamically controlled to provide vary-

ing output voltages from 0.4V to 3.4V. The circuit is

designed such that the output voltage settles in <30µs

for a full-scale change in voltage and current. The

MAX1821 is set with external resistors to provide any

fixed output voltage in the 1.25V to 5.5V range.

The MAX1820/MAX1821 include a low on-resistance

internal MOSFET switch and synchronous rectifier to

maximize efficiency and minimize external component

count; 100% duty-cycle operation allows for low dropout

of only 150mV at 600mA load, including the external

inductor resistance. The devices are offered in 10-pin

µMAX and tiny 3

4 chip-scale (UCSP™) packages.

________________________Applications

WCDMA Cell Phone Power Amplifiers

PDA, Palmtop, and Notebook Computers

Microprocessor Core Supplies

Digital Cameras

PCMCIA and Network Cards

Hand-Held Instruments

Features

♦ Dynamically Adjustable Output from 0.4V to 3.4V

(MAX1820)

♦ Programmable Output from 1.25V to 5.5V

(MAX1821)

♦ SYNC to 13MHz External Clock (MAX1820X)

♦ SYNC to 19.8MHz External Clock (MAX1820Y)

♦ NO SYNC, Internal 1MHz Oscillator (MAX1820Z)

♦ Low Quiescent Current

180µA (typ) in Skip Mode

0.1µA (typ) in Shutdown Mode

♦ No External Schottky Diode Required

♦ 600mA Guaranteed Output Current

♦ 0% to 100% Duty-Cycle Operation

♦ 150mV Dropout at 600mA Load (Including R

of External Inductor)

♦ µMAX or UCSP Packaging

MAX1820/MAX1821

WCDMA Cellular Phone 600mA

Buck Regulators

________________________________________________________________ Maxim Integrated Products 1

19-2011; Rev 2; 7/02

EVALUATION KIT

AVAILABLE

Ordering Information

PART

SYNC

FREQ (MHz)

OUTPUT VOLTAGE TEMP RANGE PIN-PACKAGE UCSP MARK

MAX1820ZEBC*

No Sync

Dynamic -40°C to +85°C3

4 UCSP AAB

MAX1820YEBC*

19.8

Dynamic -40°C to +85°C3

4 UCSP AAL

MAX1820XEBC*

Dynamic -40°C to +85°C3

4 UCSP AAM

MAX1820ZEUB

No Sync

Dynamic -40°C to +85°C 10 µMAX —

MAX1820YEUB

19.8

Dynamic -40°C to +85°C 10 µMAX —

MAX1820XEUB

Dynamic -40°C to +85°C10 µMAX —

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.

Pin Configurations appear at end of data sheet.

Typical Operating Circuits continued at end of data sheet.

SYNC

GND

SHDN

BATT

PGND

COMP

OUT

CONTROL

DAC

REF

OUT

13MHz

19.8MHz

MAX1820

SKIP

4.7µH

4.7µF

INPUT

2.6V TO

5.5V

DYNAMIC

OUTPUT

0.4V TO 3.4V

Typical Operating Circuits

*UCSP reliability is integrally linked to the user’s assembly methods, circuit board material, and environment. Refer to the UCSP

Reliability Notice in the UCSP Reliability section of this data sheet for more information.

UCSP is a trademark of Maxim Integrated Products, Inc.

Ordering Information continued at end of data sheet.

1 2 3 4 5 6 ... 17 18

Indice de contenidos

Pagina 1 - Buck Regulators

General DescriptionThe MAX1820/MAX1821 low-dropout, pulse-width-mod-ulated (PWM) DC-DC buck regulators are optimized toprovide power to the power ampl

Pagina 2

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators10 ______________________________________________________________________________________ing e

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MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators______________________________________________________________________________________ 11the l

Pagina 4

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators12 ______________________________________________________________________________________Force

Pagina 5

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators______________________________________________________________________________________ 13Appli

Pagina 6

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators14 ______________________________________________________________________________________3) Ca

Pagina 7

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators______________________________________________________________________________________ 15Outpu

Pagina 8

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators16 ______________________________________________________________________________________SYNCG

Pagina 9

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators______________________________________________________________________________________ 1712L,

Pagina 10

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck RegulatorsMaxim cannot assume responsibility for use of any circuitry other than circuitry entirely embo

Pagina 11

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators2 _______________________________________________________________________________________ABSOL

Pagina 12

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators_______________________________________________________________________________________ 3PARAM

Pagina 13

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators4 _______________________________________________________________________________________PARAM

Pagina 14

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators_______________________________________________________________________________________ 5Note

Pagina 15

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators6 _______________________________________________________________________________________Typic

Pagina 16

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators_______________________________________________________________________________________ 7MAX18

Pagina 17

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators8 _______________________________________________________________________________________0.1 1

Pagina 18

MAX1820/MAX1821WCDMA Cellular Phone 600mABuck Regulators_______________________________________________________________________________________ 9_____

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