Rainbow Electronics MAX1947 - Manual

General Description
The MAX1947 is a compact, high-efficiency, step-up DC-
DC converter that regulates output voltages from 1.8V to
3.3V to power µP/DSP cores, memory, and I/O rails in 1-
and 2-cell alkaline/NiMH/NiCd battery-powered systems.
It features an internal 800mA switch and synchronous
rectifier to achieve up to 94% efficiency and to eliminate
the need for an external Schottky diode.
High-frequency switching (up to 2MHz) results in low
ripple and small external components, while automatic
pulse skipping at light loads reduces supply current to
just 70µA for extended battery life. Maxim’s proprietary
True Shutdown™ reduces supply current to just 2µA
and fully discharges the output to ground. The convert-
er is offered in fixed-output voltages of 1.8V, 2.5V, 3.0V,
and 3.3V, requiring no feedback or compensation net-
work. A 75ms RESET output flag provides for power-on
reset (POR) and undervoltage detection. The MAX1947
is available in a space-saving 8-pin TDFN package.
Applications
MP3 Players, Pagers, and CD Players
PDAs and Organizers
Digital Still Cameras
Cordless Phones
Wireless Mice/Keyboards
Portable Medical Equipment
Other Battery-Powered Systems
Features
♦ Low Input (0.7V) and Output (1.8V) Voltage
Capability
♦ Internal Synchronous Rectifier
♦ High 94% Efficiency
♦ Fixed Output Voltages: 1.8V, 2.5V, 3V, and 3.3V
♦ Up to 2MHz Switching Allows Small External
Components and Low Output Ripple
♦ Automatic Pulse Skipping at Light Loads for
Extended Battery Life
♦ Low 70µA (typ) Operating Supply Current
(Measured at OUT)
♦ Low 2µA Logic-Controlled Shutdown
♦ True Shutdown Fully Discharges Output to
Ground
♦ Uses Only Small Ceramic Capacitors
♦ 75ms RESET Output Flag
MAX1947
Low Input/Output Voltage
Step-Up DC-DC Converter with
RESET
________________________________________________________________ Maxim Integrated Products 1
LX
PGND SHDN
8
7
BATT
OUT GND
GND
RESET
TDFN
3mm x 3mm
TOP VIEW
1
2
3
4
6
5
MAX1947
Pin Configuration
Ordering Information
MAX1947
LX
GND
BATT
OUT
PGND
10µF
2.2µF
4.7µH
V OUT
+1.8V, +2.5V,
+3.0V, +3.3V
V IN
+0.7V TO +V OUT
RESET
SHDN
Typical Application Circuit
19-3086; Rev 0; 5/04
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.
*xy represents the output voltage code (e.g., 18 =1.8V).
Standard output voltages include 3.3V (33), 3.0V (30), 2.5V
(25), and 1.8V (18). Contact the factory for other output voltages
in 100mV increments between 1.8V and 3.3V; the minimum
order quantity is 25,000 units.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE PIN-PACKAGE
MAX1947ETAxy* -40
°
C to +85
°
C 8 TDFN 3mm x 3mm
True Shutdown is a trademark of Maxim Integrated Products, Inc.