Rainbow-electronics MAX1791 Manuel d'utilisateur télécharger pdf

General Description

The MAX1762/MAX1791 PWM step-down controllers

provide high efficiency, excellent transient response,

and high DC output accuracy needed for stepping

down high-voltage batteries to generate low-voltage

CPU core, I/O, and chipset RAM supplies in notebook

computers and PDAs.

Maxim’s proprietary Quick-PWM™ pulse-width modula-

tor is a free-running constant on-time type with input

feed-forward. Its high operating frequency (300kHz)

allows small external components to be utilized in PC

board area-critical applications such as subnotebook

computers and smart phones. PWM operation occurs

at heavy loads, and automatic switchover to pulse-skip-

ping operation occurs at lighter loads. The external

high-side P-channel and low-side N-channel MOSFETs

require no bootstrap components. The MAX1762/

MAX1791 are simple, easy to compensate, and do not

have the noise sensitivity of conventional fixed-frequen-

cy current-mode PWMs.

These devices achieve high efficiency at a reduced

cost by eliminating the current-sense resistor found in

traditional current-mode PWMs. Efficiency is further

enhanced by their ability to drive synchronous-rectifier

MOSFETs. The MAX1762/MAX1791 come in a 10-pin

µMAX package and offer two fixed voltages (Dual

Mode™) for each device, 1.8V/2.5V/adj (MAX1762) and

3.3V/5.0V/adj (MAX1791).

________________________Applications

Notebooks Handy-Terminals

Subnotebooks PDAs

Digital Cameras Smart Phones

1.8V/2.5V Logic

and I/O Supplies

Features

♦ High Operating Frequency (300kHz)

♦ No Current-Sense Resistor

♦ Accurate Current Limit

♦ ±1% Total DC Error over Line and During

Continuous Conduction

♦ Dual Mode Fixed Output

1.8V/2.5V/adj (MAX1762)

3.3V/5.0V/adj (MAX1791)

♦ 0.5V to 5.5V Output Adjust Range

♦ 5V to 20V Input Range

♦ Automatic Light-Load Pulse Skipping Operation

♦ Free-Running On-Demand PWM

♦ Foldback Mode™ UVLO

♦ PFET/NFET Synchronous Buck

♦ 4.65V at 25mA Linear Regulator Output

♦ 5µA Shutdown Supply Current

♦ 230µA Quiescent Supply Current

♦ 10-Pin µMAX Package

MAX1762/MAX1791

High-Efficiency, 10-Pin µMAX, Step-Down

Controllers for Notebooks

________________________________________________________________ Maxim Integrated Products 1

19-1923; Rev 0; 1/01

Ordering Information

PART TEMP. RANGE PIN-PACKAGE

MAX1762EUB -40°C to +85°C 10 µMAX

MAX1791EUB -40°C to +85°C 10 µMAX

GND

OUT

REF

SHDN

BATT

(5V TO 20V)

OUT

1.8V/3.3V

MAX1762

MAX1791

Typical Operating Circuit

DLOUT

REF

MAX1762

MAX1791

MAX

TOP VIEW

GNDSHDN

Pin Configuration

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,

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

Quick-PWM, Dual Mode, and Foldback Mode are a trade-

marks of Maxim Integrated Products.

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Résumé du contenu

Page 1 - Controllers for Notebooks

General DescriptionThe MAX1762/MAX1791 PWM step-down controllersprovide high efficiency, excellent transient response,and high DC output accuracy need

Page 2

MAX1762/MAX1791High-Efficiency, 10-Pin µMAX, Step-Down Controllers for Notebooks10 ___________________________________________________________________

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