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.

________________General Description

The MAX1630A–MAX1635A are buck-topology, step-

down, switch-mode, power-supply controllers that gener-

ate logic-supply voltages in battery-powered systems.

These high-performance, dual-/triple-output devices

include on-board power-up sequencing, power-good

signaling with delay, digital soft-start, secondary winding

control, low-dropout circuitry, internal frequency-com-

pensation networks, and automatic bootstrapping.

Up to 96% efficiency is achieved through synchronous

rectification and Maxim’s proprietary Idle Mode™ control

scheme. Efficiency is greater than 80% over a 1000:1

load-current range, which extends battery life in system-

suspend or standby mode. Excellent dynamic response

corrects output load transients caused by the latest

dynamic-clock CPUs within five 300kHz clock cycles.

Strong 1A on-board gate drivers ensure fast external

n-channel MOSFET switching.

These devices feature a logic-controlled and synchroniz-

able, fixed-frequency, pulse-width-modulation (PWM)

operating mode. This reduces noise and RF interference

in sensitive mobile communications and pen-entry appli-

cations. Asserting the SKIP pin enables fixed-frequency

mode for lowest noise under all load conditions.

The MAX1630A–MAX1635A include two PWM regulators,

adjustable from 2.5V to 5.5V with fixed 5.0V and 3.3V

modes. All these devices include secondary feedback

regulation, and the MAX1630A/MAX1632A/MAX1633A/

MAX1635A each contain 12V/120mA linear regulators.

The MAX1631A/MAX1634A include a secondary feed-

back input (SECFB), plus a control pin (STEER) that

selects which PWM (3.3V or 5V) receives the secondary

feedback signal. SECFB provides a method for adjusting

the secondary winding voltage regulation point with an

external resistor-divider, and is intended to aid in creating

auxiliary voltages other than fixed 12V.

The MAX1630A/MAX1631A/MAX1632A contain internal

output overvoltage and undervoltage protection features.

The MAX1630A family has improved RF immunity over

the MAX1630 family.

________________________Applications

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

Desktop CPU Local DC-DC Converters

____________________________Features

♦ 96% Efficiency

♦ +4.2V to +30V Input Range

♦ 2.5V to 5.5V Dual Adjustable Outputs

♦ Selectable 3.3V and 5V Fixed or Adjustable

Outputs (Dual Mode™)

♦ 12V Linear Regulator

♦ Adjustable Secondary Feedback

(MAX1631A/MAX1634A)

♦ 5V/50mA Linear Regulator Output

♦ Precision 2.5V Reference Output

♦ Programmable Power-Up Sequencing

♦ Power-Good (RESET) Output

♦ Output Overvoltage Protection

(MAX1630A/MAX1631A/MAX1632A)

♦ Output Undervoltage Shutdown

(MAX1630A/MAX1631A/MAX1632A)

♦ 200kHz/300kHz Low-Noise, Fixed-Frequency

Operation

♦ Low-Dropout, 99% Duty-Factor Operation

♦ 2.5mW Typical Quiescent Power (+12V Input,

Both SMPSs On)

♦ 4µA Typical Shutdown Current

♦ 28-Pin SSOP Package

Multi-Output, Low-Noise Power-Supply

Controllers for Notebook Computers

________________________________________________________________ Maxim Integrated Products

1

5V

LINEAR

12V

LINEAR

POWER-UP

SEQUENCE

POWER-

GOOD

3.3V

SMPS

5V

SMPS

RESET

ON/OFF

+5V (RTC)

+3.3V

INPUT

+5V

+12V

________________Functional Diagram

19-3518; Rev 1; 8/05

PART

MAX1630AEAI

-40°C to +85°C

TEMP RANGE

PIN-PACKAGE

28 SSOP

EVALUATION

KIT

AVAILABLE

_______________Ordering Information

Ordering Information continued at end of data sheet.

Pin Configurations and Selector Guide appear at end of data

sheet.

Idle Mode and Dual Mode are trademarks of Maxim Integrated

Products, Inc.