_______________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

♦ 1μA Typ Shutdown Current

Step-Down Controllers with

Synchronous Rectifier for CPU Power

________________________________________________________________ Maxim Integrated Products

1

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.

19-0221; Rev 4; 9/05

___________________Pin Configuration

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

DH

LX

BST

DL

GND

REF

(SECFB) SKIP

SS

TOP VIEW

MAX796

MAX797

MAX799

PGND

VL

V+

CSL

( ) ARE FOR MAX796/MAX799.

CSH

FB

SHDN

SYNC

DIP/SO

Dice*

16 Narrow SO

16 Plastic DIP

PIN-PACKAGE

TEMP RANGE

0°C to +70°C

0°C to +70°C

0°C to +70°C

MAX796C/D

MAX796CSE

MAX796CPE

16 CERDIP

16 Narrow SO

16 Plastic DIP

-40°C to +85°C

-40°C to +85°C

-55°C to +125°C

MAX796MJE

MAX796ESE

MAX796EPE

Ordering Information continued at end of data sheet.

*Contact factory for dice specifications.

_______________Ordering Information

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.

EVALU

ATION

KIT

AVAIL

ABLE