19-3518; Rev 1; 8/05
KIT
ATION
EVALU
ILABLE
AVA
Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
____________________________Features
The MAX1630A–MAX1635A are buck-topology, stepdown, switch-mode, power-supply controllers that generate 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-compensation 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 systemsuspend 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 synchronizable, fixed-frequency, pulse-width-modulation (PWM)
operating mode. This reduces noise and RF interference
in sensitive mobile communications and pen-entry applications. 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 feedback 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.
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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
_______________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
+12V
+5V (RTC)
5V
LINEAR
12V
LINEAR
3.3V
SMPS
5V
SMPS
POWER-UP
SEQUENCE
POWERGOOD
________________________Applications
Notebook and Subnotebook Computers
+3.3V
PDAs and Mobile Communicators
+5V
Desktop CPU Local DC-DC Converters
Pin Configurations and Selector Guide appear at end of data
sheet.
ON/OFF
RESET
Idle Mode and Dual Mode are trademarks of Maxim Integrated
Products, Inc.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX1630A–MAX1635A
________________General Description
