Rainbow Electronics MAX1734 - Manual

General Description
The MAX1733/MAX1734 step-down DC-DC converters
deliver over 250mA to outputs as low as 1.25V. These
converters use a unique proprietary current-limited con-
trol scheme that achieves over 90% efficiency. These
devices maintain extremely low quiescent supply cur-
rent (40µA), and their high 1.2MHz (max) operating fre-
quency permits small, low-cost external components.
This combination of features makes the MAX1733/
MAX1734 excellent high-efficiency alternatives to linear
regulators in space-constrained applications.
Internal synchronous rectification greatly improves effi-
ciency and eliminates the external Schottky diode
required in conventional step-down converters. Both
devices also include internal digital soft-start to limit
input current upon startup and reduce input capacitor
requirements.
The MAX1733 provides an adjustable output voltage
(1.25V to 2.0V). The MAX1734 provides factory-preset
output voltages (see Selector Guide). Both are avail-
able in space-saving 5-pin SOT23 packages.
Applications
Cellular, PCS, and Cordless Telephones
PDAs, Palmtops, and Handy-Terminals
Battery-Powered Equipment
Features
♦ 250mA Guaranteed Output Current
♦ Synchronous Rectifier for Over 90% Efficiency
♦ Tiny 5-Pin SOT23 Package
♦ 40µA Quiescent Supply Current
♦ 0.01µA Logic-Controlled Shutdown
♦ Up to 1.2MHz Switching Frequency
♦ Fixed 1.8V or 1.5V Outputs (MAX1734)
♦ Adjustable Output Voltage (MAX1733)
♦ ±1.5% Initial Accuracy
♦ 2.7V to 5.5V Input Range
♦ Soft-Start Limits Startup Current
MAX1733/MAX1734
Low-Voltage, Step-Down DC-DC Converters
in SOT23
________________________________________________________________ Maxim Integrated Products 1
GND
OUT (FB)
( ) ARE FOR MAX1733 ONLY.
SHDN
1 5 LX IN
MAX1733
MAX1734
SOT23-5
TOP VIEW
2
3 4
Pin Configuration
OUT
V OUT AT
250mA
INPUT
+2.7V TO +5.5V
LX IN
MAX1734
SHDN
GND
10 µH
22 µF 2.2 µF
Typical Operating Circuit
19-1586; Rev 0; 7/00
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
Note: The MAX1734 offers two output voltages. See the Selector
Guide, then insert the proper designator into the blanks above to
complete the part number.
Ordering Information
PART TEMP. RANGE PIN-PACKAGE
MAX1733EUK-T -40 °C to +85°C 5 SOT23-5
M A X1 7 3 4 E U K_ _- T -40 °C to +85°C 5 SOT23-5
Selector Guide
PART V OUT (V) TOP MARK
MAX1733EUK Adjustable ADKY
MAX1734EUK18 1.8 ADKW
MAX1734EUK15 1.5 ADKX