19-3518; Rev 1; 8/05
Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
________________General Description
____________________________Features
♦ 96% Efficiency
♦ +4.2V to +30V Input Range
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.
♦ 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)
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.
♦ 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)
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.
♦ 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
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.
_______________Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX1630AEAI
-40°C to +85°C
28 SSOP
+Denotes lead-free package.
Ordering Information continued at end of data sheet.
________________Functional Diagram
INPUT
The MAX1630A/MAX1631A/MAX1632A contain internal
output overvoltage and undervoltage protection features.
The MAX1630A family has improved RF immunity over
the MAX1630 family.
+12V
+5V (RTC)
5V
12V
LINEAR
LINEAR
________________________Applications
Notebook and Subnotebook Computers
+3.3V
+5V
3.3V
5V
SMPS
SMPS
PDAs and Mobile Communicators
Desktop CPU Local DC-DC Converters
Pin Configurations and Selector Guide appear at end of data
sheet.
POWER-UP
SEQUENCE
POWER-
GOOD
ON/OFF
RESET
Idle Mode and Dual Mode are trademarks of Maxim Integrated
Products, Inc.
________________________________________________________________ Maxim Integrated Products
1
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.