19-3518; Rev 1; 8/05
KIT
ATION
EVALU
BLE
AVAILA
Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
____________________________Features
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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
________________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.
MAX1630A–MAX1635A
_______________Ordering Information
PART
MAX1630AEAI
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
28 SSOP
+Denotes
lead-free package.
Ordering Information continued at end of data sheet.
________________Functional Diagram
INPUT
+5V (RTC)
5V
LINEAR
12V
LINEAR
+12V
________________________Applications
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
Desktop CPU Local DC-DC Converters
Pin Configurations and Selector Guide appear at end of data
sheet.
Idle Mode and Dual Mode are trademarks of Maxim Integrated
Products, Inc.
________________________________________________________________
Maxim Integrated Products
1
+3.3V
3.3V
SMPS
5V
SMPS
+5V
ON/OFF
POWER-UP
SEQUENCE
POWER-
GOOD
RESET
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.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
