Rainbow-electronics MAX799 Manual de usuario descargar pdf

_______________General Description

The MAX796/MAX797/MAX799 high-performance, step-

down DC-DC converters with single or dual outputs

provide main CPU power in battery-powered systems.

These buck controllers achieve 96% efficiency by using

synchronous rectification and Maxim’s proprietary Idle

Mode™ control scheme to extend battery life at full-load

(up to 10A) and no-load outputs. Excellent dynamic

response corrects output transients caused by the latest

dynamic-clock CPUs within five 300kHz clock cycles.

Unique bootstrap circuitry drives inexpensive N-channel

MOSFETs, reducing system cost and eliminating the

crowbar switching currents found in some PMOS/NMOS

switch designs.

The MAX796/MAX799 are specially equipped with a sec-

ondary feedback input (SECFB) for transformer-based

dual-output applications. This secondary feedback path

improves cross-regulation of positive (MAX796) or nega-

tive (MAX799) auxiliary outputs.

The MAX797 has a logic-controlled and synchronizable

fixed-frequency pulse-width-modulating (PWM) operating

mode, which reduces noise and RF interference in sensi-

tive mobile-communications and pen-entry applications.

The SKIP override input allows automatic switchover to

idle-mode operation (for high-efficiency pulse skipping) at

light loads, or forces fixed-frequency mode for lowest noise

at all loads.

The MAX796/MAX797/MAX799 are all available in 16-

pin DIP and narrow SO packages. See the table below

to compare these three converters.

________________________Applications

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

Cellular Phones

____________________________Features

♦ 96% Efficiency

♦ 4.5V to 30V Input Range

♦ 2.5V to 6V Adjustable Output

♦ Preset 3.3V and 5V Outputs (at up to 10A)

♦ Multiple Regulated Outputs

♦ +5V Linear-Regulator Output

♦ Precision 2.505V Reference Output

♦ Automatic Bootstrap Circuit

♦ 150kHz/300kHz Fixed-Frequency PWM Operation

♦ Programmable Soft-Start

♦ 375µA Typ Quiescent Current (V

= 12V, V

OUT

= 5V)

♦ 1µA Typ Shutdown Current

MAX796/MAX797/MAX799

Step-Down Controllers with

Synchronous Rectifier for CPU Power

________________________________________________________________

Maxim Integrated Products

PART

MAX799

MAIN OUTPUT SPECIAL FEATURE

3.3V/5V or adj.

Regulates negative secondary

voltage (such as -5V)

MAX797 3.3V/5V or adj. Logic-controlled low-noise mode

MAX796 3.3V/5V or adj.

Regulates positive secondary

voltage (such as +12V)

Idle Mode is a trademark of Maxim Integrated Products.

†

U.S. and foreign patents pending.

19-0221; Rev 3a; 11/97

EVALUATION KIT MANUALS

FOLLOW DATA SHEET

__________________Pin Configuration

BST

GND

REF

(SECFB) SKIP

TOP VIEW

MAX796

MAX797

MAX799

PGND

V+

CSL

( ) ARE FOR MAX796/ MAX799.

CSH

SHDN

SYNC

DIP/SO

Dice*

16 Narrow SO

16 Plastic DIP

PIN-PACKAGETEMP. RANGE

0°C to +70°C

0°C to +70°CMAX796C/D

MAX796CSE

MAX796CPE

PART

†

16 CERDIP

16 Narrow SO

16 Plastic DIP-40°C to +85°C

-40°C to +85°C

-55°C to +125°CMAX796MJE

MAX796ESE

MAX796EPE

Ordering Information continued at end of data sheet.

*Contact factory for dice specifications.

______________Ordering Information

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

For small orders, phone 408-737-7600 ext. 3468.

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Indice de contenidos

Pagina 1 - Step-Down Controllers with

_______________General DescriptionThe MAX796/MAX797/MAX799 high-performance, step-down DC-DC converters with single or dual outputsprovide main CPU po

Pagina 2

MAX796/MAX797/MAX799Step-Down Controllers with Synchronous Rectifier for CPU Power 10 ________________________________________________________________

Pagina 3