Rainbow Electronics MAX1692 - Manual

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General Description
The MAX1692 is a low-noise, pulse-width-modulated
(PWM), DC-DC step-down converter. It powers logic
and transmitters in small wireless systems such as cellu-
lar phones, communicating PDAs, and handy-terminals.
The device features an internal synchronous rectifier for
high efficiency; it requires no external Schottky diode.
Excellent noise characteristics and fixed-frequency
operation provide easy post-filtering. The MAX1692 is
ideally suited for Li-Ion battery applications. It is also
useful for +3V or +5V fixed input applications.
The device operates in one of four modes. Forced PWM
mode operates at a fixed frequency regardless of the
load. Synchronizable PWM mode allows an external
switching frequency to control and minimize harmonics.
Idle Mode™ (PWM/PFM) extends battery life by switch-
ing to a PFM pulse-skipping mode during light loads.
Shutdown mode places the device in standby, reduc-
ing quiescent supply current to under 0.1µA.
The MAX1692 can deliver over 600mA. The output volt-
age can be adjusted from 1.25V to V
IN with the input
range of +2.7V to +5.5V. Other features of the
MAX1692 include high efficiency, low dropout voltage,
and a 1.2%-accurate 1.25V reference. It is available in
a space-saving 10-pin µMAX package with a height of
only 1.11mm.
Applications
Cellular Phones CPU I/O Supplies
Cordless Phones Notebook Chipset Supplies
PDAs and Handy-Terminals Battery-Operated Devices
(1 Li-Ion or 3 NiMH/NiCd)
Features
♦ +2.7V to +5.5V Input Range
♦ Adjustable Output from 1.25V to V IN
♦ 600mA Guaranteed Output Current
♦ 95% Efficiency
♦ No Schottky Diode Required
♦ 85µA Quiescent Current
♦ 100% Duty Cycle in Dropout
♦ 750kHz Fixed-Frequency PWM Operation
♦ Synchronizable Switching Frequency
♦ Accurate Reference: 1.25V (±1.2%)
♦ Small 10-Pin µMAX Package
MAX1692
Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
________________________________________________________________ Maxim Integrated Products 1
1
2
3
4
5
10
9
8
7
6
PGND
LX
SHDN
SYNC/PWM REF
GND
BP
IN
MAX1692
TOP VIEW
LIM FB
µ
MAX
19-1400; Rev 0; 11/98
PART
MAX1692EUB -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
10 µMAX
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
Idle Mode is a trademark of Maxim Integrated Products.
Pin Configuration
Ordering Information
Typical Operating Circuit
MAX1692 FB
SYNC/PWM
PGND
BP
LIM
LX
SHDN
IN
L
C2
R1
R2
C4
C3
C1
V IN = 2.7V TO 5.5V V OUT = 1.25V TO V IN
AGND REF