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General Description

The MAX668/MAX669 constant-frequency, pulse-width-

modulating (PWM), current-mode DC-DC controllers are

designed for a wide range of DC-DC conversion applica-

tions including step-up, SEPIC, flyback, and isolated-

output configurations. Power levels of 20W or more can

be controlled with conversion efficiencies of over 90%.

The 1.8V to 28V input voltage range supports a wide

range of battery and AC-powered inputs. An advanced

BiCMOS design features low operating current (220µA),

adjustable operating frequency (100kHz to 500kHz),

soft-start, and a SYNC input allowing the MAX668/

MAX669 oscillator to be locked to an external clock.

DC-DC conversion efficiency is optimized with a low

100mV current-sense voltage as well as with Maxim’s

proprietary Idle Mode™ control scheme. The controller

operates in PWM mode at medium and heavy loads for

lowest noise and optimum efficiency, then pulses only as

needed (with reduced inductor current) to reduce oper-

ating current and maximize efficiency under light loads.

A logic-level shutdown input is also included, reducing

supply current to 3.5µA.

The MAX669, optimized for low input voltages with a

guaranteed start-up voltage of 1.8V, requires boot-

strapped operation (IC powered from boosted output). It

supports output voltages up to 28V. The MAX668 oper-

ates with inputs as low as 3V and can be connected in

either a bootstrapped or non-bootstrapped (IC powered

from input supply or other source) configuration. When

not bootstrapped, it has no restriction on output voltage.

Both ICs are available in an extremely compact 10-pin

µMAX package.

Features

♦ 1.8V Minimum Start-Up Voltage (MAX669)

♦ Wide Input Voltage Range (1.8V to 28V)

♦ Tiny 10-Pin µMAX Package

♦ Current-Mode PWM and Idle Mode™ Operation

♦ Efficiency over 90%

♦ Adjustable 100kHz to 500kHz Oscillator or

SYNC Input

♦ 220µA Quiescent Current

♦ Logic-Level Shutdown

♦ Soft-Start

Applications

Cellular Telephones

Telecom Hardware

LANs and Network Systems

POS Systems

MAX668/MAX669

1.8V to 28V Input, PWM Step-Up

Controllers in µMAX

________________________________________________________________

Maxim Integrated Products

19-4778; Rev 0a; 8/98

PART

MAX668EUB

MAX669EUB

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

10 µMAX

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

Idle Mode is a trademark of Maxim Integrated Products.

Ordering Information

Typical Operating Circuit

MAX669

FREQ

CS+

SYNC/

SHDN

PGND

GND

EXT

LDO

REF

OUT

= 28V

= 1.8V to 28V

SYNC/SHDN

EXT

PGNDREF

GND

FREQ

LDO

MAX668

MAX669

µMAX

TOP VIEW

CS+FB

Pin Configuration

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

1 2 3 4 5 6 ... 17 18

MAX668/MAX669 1
Controllers in µMAX 1

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Página 1 - Controllers in µMAX

General DescriptionThe MAX668/MAX669 constant-frequency, pulse-width-modulating (PWM), current-mode DC-DC controllers aredesigned for a wide range of

Página 2

MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX 10 __________________________________________________________________________________

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Non-Bootstrapped OperationWith non-bootstrapped operation, the IC is poweredfrom the input voltage (VIN) or another source, such asa logic supply. Non

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MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX 12 __________________________________________________________________________________

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SYNC/SHDNand FREQ InputsThe SYNC/SHDN pin provides both external-clock syn-chronization (if desired) and shutdown control. WhenSYNC/SHDN is low, all I

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MAX668/MAX669 given output ripple. An inductance value larger thanLIDEALmay also be used, but output-filter capacitancemust be increased by the same p

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not be adequate for low output voltage ripple. Sinceoutput ripple in boost DC-DC designs is dominated bycapacitor equivalent series resistance (ESR),

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MAX668/MAX669 larger or smaller than the output voltage, such as whenconverting four NiMH, NiCd, or Alkaline cells to a 5Voutput. The SEPIC configurat

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Chip InformationTRANSISTOR COUNT: 1861MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX _______________________________________________

Página 10

MAX668/MAX669 Package Information1.8V to 28V Input, PWM Step-Up Controllers in µMAX 18 _______________________________________________________________

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MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX 2 ___________________________________________________________________________________

Página 12

VMAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX ____________________________________________________________________________________

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MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX 4 ___________________________________________________________________________________

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MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX _____________________________________________________________________________________

Página 15

MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX 6 ___________________________________________________________________________________

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MAX668/MAX669 1.8V to 28V Input, PWM Step-Up Controllers in µMAX _____________________________________________________________________________________

Página 17

Detailed DescriptionThe MAX668/MAX669 current-mode PWM controllersoperate in a wide range of DC-DC conversion applica-tions, including boost, SEPIC, f

Página 18

PWM ControllerThe heart of the MAX668/MAX669 current-mode PWMcontroller is a BiCMOS multi-input comparator thatsimultaneously processes the output-err

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Rainbow-electronics MAX669 Manual do Utilizador

Consulte online ou descarregue Manual do Utilizador para Sensores Rainbow-electronics MAX669. Rainbow Electronics MAX669 User Manual Manual do Utilizador

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