19-0480; Rev 4; 8/05
KIT
ATION
EVALU
E
AILABL
AV
Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
____________________________Features
The MAX1630–MAX1635 are buck-topology, step-down,
switch-mode, power-supply controllers that generate
logic-supply voltages in battery-powered systems. These
high-performance, dual/triple-output devices include onboard power-up sequencing, power-good signaling with
delay, digital soft-start, secondary winding control, lowdropout 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 MAX1630–MAX1635 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 MAX1630/MAX1632/MAX1633/
MAX1635 each contain 12V/120mA linear regulators. The
MAX1631/MAX1634 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 MAX1630/MAX1631/MAX1632 contain internal output overvoltage and undervoltage protection 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
(MAX1631/MAX1634)
5V/50mA Linear Regulator Output
Precision 2.5V Reference Output
Programmable Power-Up Sequencing
Power-Good (RESET) Output
Output Overvoltage Protection
(MAX1630/MAX1631/MAX1632)
Output Undervoltage Shutdown
(MAX1630/MAX1631/MAX1632)
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
TEMP RANGE
PIN-PACKAGE
MAX1630CAI
PART
0°C to +70°C
28 SSOP
MAX1630CAI+
0°C to +70°C
28 SSOP
MAX1630EAI+
-40°C to +85°C
28 SSOP
Ordering Information continued at end of data sheet.
+ Denotes lead-free package.
________________Functional Diagram
INPUT
+12V
+5V (RTC)
5V
LINEAR
12V
LINEAR
3.3V
SMPS
Notebook and Subnotebook Computers
5V
SMPS
POWER-UP
SEQUENCE
POWERGOOD
PDAs and Mobile Communicators
Desktop CPU Local DC-DC Converters
+3.3V
+5V
Pin Configurations and Selector Guide appear at end of data
sheet.
ON/OFF
Idle Mode and Dual Mode are trademarks of Maxim Integrated
Products.
RESET
________________________________________________________________ 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
MAX1630–MAX1635
________________General Description