MAX1733 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – Low-Voltage, Step-Down DC-DC Converters in SOT23

19-1586; Rev 0; 7/00
Low-Voltage, Step-Down DC-DC Converters
in SOT23
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
Typical Operating Circuit
Features
o 250mA Guaranteed Output Current
o Synchronous Rectifier for Over 90% Efficiency
o Tiny 5-Pin SOT23 Package
o 40µA Quiescent Supply Current
o 0.01µA Logic-Controlled Shutdown
o Up to 1.2MHz Switching Frequency
o Fixed 1.8V or 1.5V Outputs (MAX1734)
o Adjustable Output Voltage (MAX1733)
o ±1.5% Initial Accuracy
o 2.7V to 5.5V Input Range
o Soft-Start Limits Startup Current
Ordering Information
PART
MAX1733EUK-T
MAX1734EUK_ _-T
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
5 SOT23-5
5 SOT23-5
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.
Selector Guide
PART
MAX1733EUK
MAX1734EUK18
MAX1734EUK15
V_OUT (V)
Adjustable
1.8
1.5
TOP MARK
ADKY
ADKW
ADKX
Pin Configuration
INPUT
+2.7V TO +5.5V
2.2µF
10µH
IN
LX
MAX1734
SHDN
OUT
V_OUT AT
250mA
22µF
TOP VIEW
IN 1
5 LX
MAX1733
GND 2 _MAX1734
GND
SHDN 3
4 OUT (FB)
( ) ARE FOR MAX1733 ONLY.
SOT23-5
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