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General Description

The MAX1684/MAX1685 are high-efficiency, internal-

switch, pulse-width modulation (PWM) step-down switch-

ing regulators intended to power cellular phones,

communicating PDAs, and handy-terminals. These

devices deliver a guaranteed 1A output current from two

lithium-ion (Li+) batteries. Their wide-input voltage range

of 2.7V to 14V gives design flexibility and allows batteries

to charge from a wall cube, since the ICs operate at the

higher voltages that occur when the battery is removed.

The output voltage is preset to 3.3V or can be externally

adjusted from 1.25V to V

The low on-resistance power switch and built-in synchro-

nous rectifier provide high efficiencies of up to 96%.

There are four modes of operation: fixed-frequency, nor-

mal, low-power, and shutdown. The fixed-frequency

PWM mode of operation offers excellent noise character-

istics. The normal mode maintains high efficiency at all

loads. The low-power mode is used to conserve power in

standby or when full load is not required. The shutdown

mode is used to power down the device for minimal cur-

rent draw.

The MAX1684 runs at 300kHz for applications that

require highest efficiency. The MAX1685 runs at

600kHz to allow the use of smaller external compo-

nents. These devices can also be synchronized to an

external clock. Other features include a 100% duty

cycle for low-dropout applications, an auxiliary 3V/5mA

output, and a 1% accurate reference.

Both devices are available in a space-saving 16-QSOP

package. An evaluation kit is also available to help

speed designs. For a similar device in a 10-pin µMAX

package with lower input voltage requirements (5.5V

max), refer to the MAX1692 data sheet.

Applications

Cellular Phones

Two-Way Radios and Walkie-Talkies

Computer Peripherals

Personal Communicators

PDAs and Handy-Terminals

Features

♦ Up to 96% Efficiency

♦ 1A Guaranteed Output Current

♦ 100% Duty Cycle in Dropout

♦ 2.7V to 14V Input Range (15V Absolute Max)

♦ ±1% Accurate Reference Output

♦ 0.24Ω P-Channel On-Resistance

♦ Synchronizable Switching Frequency

♦ Fixed-Frequency PWM Operation

300kHz (MAX1684)

600kHz (MAX1685)

♦ 150µA Normal-Mode Quiescent Current

♦ 25µA Low-Power Mode Quiescent Current

♦ 2µA Shutdown Current

♦ Dual Mode™ Fixed 3.3V (±1%) Output or

Adjustable Output (1.25V to V

)

♦ Small 16-QSOP Package

♦ Auxiliary Output (CVL): 3V/5mA

MAX1684/MAX1685

Low-Noise, 14V Input, 1A, PWM

Step-Down Converters

MAX1684

MAX1685

LXIN

AIN

GND

OUTPUT

3.3V AT 1A

INPUT

2.7V TO 14V

BOOT

SHDN

CVH

CVL

STBY

SYNC/PWM

FB CC REF

19-1454; Rev 2; 7/01

PART

MAX1684EEE

MAX1685EEE

-40°C to +85°C

TEMP RANGE PIN-PACKAGE

16 QSOP

EVALUATION KIT

AVAILABLE

Typical Operating Circuit

Ordering Information

Pin Configuration appears at end of data sheet.

Dual Mode is a trademark of Maxim Integrated Products, Inc.

________________________________________________________________ Maxim Integrated Products 1

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.

1 2 3 4 5 6 ... 13 14

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Página 1 - Step-Down Converters

General DescriptionThe MAX1684/MAX1685 are high-efficiency, internal-switch, pulse-width modulation (PWM) step-down switch-ing regulators intended to

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters 10 _________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters ____________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters MAX1684MAX1685LXAININCVHFBLC1MBRS130LT3R1R2BOOTPGNDAGNDCCSHDNSTBY0.1µF22µF0.1µF100µF

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Inverting OutputInterchanging the ground and VOUTconnections yieldsa negative voltage supply (Figure 4). The componentselections are the same as for a

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters Maxim cannot assume responsibility for use of any circuitry other than circuitry ent

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters 2 __________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters ____________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters 4 __________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters ____________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters 6 __________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters ____________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters 8 __________________________________________________________________________________

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MAX1684/MAX1685Low-Noise, 14V Input, 1A, PWM Step-Down Converters ____________________________________________________________________________________

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Rainbow-electronics MAX1685 Manual do Utilizador

Consulte online ou descarregue Manual do Utilizador para Sensores Rainbow-electronics MAX1685. Rainbow Electronics MAX1685 User Manual Manual do Utilizador

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