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________________General Desc ription
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 on-
board power-up sequencing, power-good signaling with
delay, digital soft-start, secondary winding control, low-
dropout circuitry, internal frequency-compensation net-
works, 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
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 sig-
nal. SECFB provides a method for adjusting the sec-
ondary 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 out-
put overvoltage and undervoltage protection features.
________________________Applic ations
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
Desktop CPU Local DC-DC Converters
____________________________Features
o
96% Efficiency
o
+4.2V to +30V Input Range
o
2.5V to 5.5V Dual Adjustable Outputs
o
Selectable 3.3V and 5V Fixed or Adjustable
Outputs (Dual Mode)
o
12V Linear Regulator
o
Adjustable Secondary Feedback
(MAX1631/MAX1634)
o
5V/50mA Linear Regulator Output
o
Precision 2.5V Reference Output
o
Programmable Power-Up Sequencing
o
Power-Good (RESET) Output
o
Output Overvoltage Protection
(MAX1630/MAX1631/MAX1632)
o
Output Undervoltage Shutdown
(MAX1630/MAX1631/MAX1632)
o
200kHz/300kHz Low-Noise, Fixed-Frequency
Operation
o
Low-Dropout, 99% Duty-Factor Operation
o
2.5mW Typical Quiescent Power (+12V input, both
SMPSs on)
o
4μA Typical Shutdown Current
o
28-Pin SSOP Package
M
Multi-Output, Low-Noise Power-S upply
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
________________Func tional Diagram
19-0480; Rev 3; 4/97
EVALUATION KIT
AVAILABLE
PART
MAX1630
CAI
MAX1630EAI
Ordering Information continued on last page.
-40°C to +85°C
0°C to +70°C
TEMP. RANGE
PIN-PACKAGE
28 SSOP
28 SSOP
_______________Ordering Information
Pin Configurations and Selector Guide appear at end of data
sheet.
Idle Mode and Dual Mode are trademarks of Maxim Integrated
Products.