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MAX1733EUK+T

P1-P3P4-P6P7-P8
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
15LXIN
MAX1733
MAX1734
SOT23-5
TOP VIEW
2
34
Pin Configuration
OUT
V
OUT
AT
250mA
INPUT
+2.7V TO +5.5V
LX
IN
MAX1734
SHDN
GND
10µH
22µF
2.2µF
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
MAX1733/MAX1734
Low-Voltage, Step-Down DC-DC Converters
in SOT23
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= +2.7V to +5.5V, SHDN = IN, T
A
= 0°C to +85°C. Typical values are at T
A
= +25°C, unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, SHDN to GND .....................................................-0.3V to +6V
OUT, FB, LX to GND....................................-0.3V to (V
IN
+ 0.3V)
OUT Short Circuit to GND ..........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range V
IN
2.7 5.5 V
Startup Voltage V
START
2.0 V
V
IN
rising 1.85 1.95
UVLO Threshold V
UVLO
V
IN
falling 1.55 1.65
V
UVLO Hysteresis 200 mV
Quiescent Supply Current I
IN
No switching, no load (FB/OUT above trip
point)
40 70 µA
Shutdown Supply Current I
SHDN
SHDN = GND 0.01 4 µA
Outp ut V ol tag e Range ( MAX 1733) V
OUT
1.25 2.0 V
I
OUT
= 0, T
A
= +25°C -1.5 +1.5
Output Voltage Accuracy
(MAX1734)
I
OUT
= 0 to 250mA -3 +3
%
Load Regulation I
OUT
= 0 to 250mA 0 %/mA
Line Regulation V
IN
= 2.7V to 5.5V 0 %/V
OUT Sense Current (MAX1734) V
OUT
= V
REG
, V
IN
= V
SHDN
= 5V 4 8 µA
T
A
= +25°C, V
IN
= 3.6V 1.231 1.250 1.269
FB Feedback Threshold
(MAX1733)
V
FB
V
IN
= 3.6V 1.220 1.280
V
FB Leakage Current (MAX1733) I
FB
V
FB
= 1.5V 0.001 0.2 µA
SHDN Input High Voltage V
IH
2.7V < V
IN
< 5.5V 1.6 V
SHDN Input Low Voltage V
IL
2.7V < V
IN
< 5.5V 0.4 V
SHDN Leakage Current I
SHDN
SHDN = GND or IN 0.001 1 µA
High-Side Current Limit I
LIMP
300 425 535 mA
Low-Side Current Limit I
LIMN
200 325 430 mA
I
LX
= -50mA, V
IN
= 3.0V 0.7 1.4
High-Side On-Resistance R
ONP
I
LX
= -50mA, V
IN
= 5.5V 0.5 1.1
Ω
I
LX
= -50mA, V
IN
= 3.0V 1.0 2
Rectifier On-Resistance R
ONN
I
LX
= -50mA, V
IN
= 5.5V 0.8 1.6
Ω
Rectifier Off-Current Threshold I
LXOFF
40 mA
LX Leakage Current I
LXLEAK
V
IN
= 5.5V, V
LX
= 0 to V
IN
0.1 5 µA
LX Reverse Leakage Current I
LXLK
,
R
IN unconnected, V
LX
= 5.5V, SHDN = GND 0.1 5 µA
Minimum On-Time t
ON
(
MIN
)
V
IN
= 3.6V 0.28 0.4 0.5 µs
Minimum Off-Time
t
OFF( M IN)
V
IN
= 3.6V 0.28 0.4 0.5 µs
MAX1733/MAX1734
Low-Voltage, Step-Down DC-DC Converters
in SOT23
_______________________________________________________________________________________ 3
Note 1: All devices are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by design.
ELECTRICAL CHARACTERISTICS
(V
IN
= +2.7V to +5.5V, SHDN = IN, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
Input Voltage Range V
IN
2.7 5.5 V
Startup Voltage V
START
2.0 V
V
IN
rising, 200mV typical hysteresis 1.95
UVLO Threshold V
UVLO
V
IN
falling 1.55
V
Quiescent Supply Current I
IN
No switching (FB/OUT above trip point) 70 µA
Shutdown Supply Current I
SHDN
SHDN = GND 4 µA
Outp ut V ol tag e Range ( MAX 1733) V
OUT
1.25 2.0 V
Output Voltage Accuracy
(MAX1734)
I
OUT
= 0 to 250mA -3 +3 %
OUT Sense Current (MAX1734) I
OUT
V
OUT
= V
REG
, V
IN
= V
SHDN
= 5V 8 µA
FB Feedback Threshold
(MAX1733)
V
FB
V
IN
= 3.6V 1.210 1.280 V
FB Leakage Current (MAX1733) I
FB
V
FB
= 1.5V 0.2 µA
SHDN Input High Voltage V
IH
2.7V < V
IN
< 5.5V 1.6 V
SHDN Input Low Voltage V
IL
2.7V < V
IN
< 5.5V 0.4 V
SHDN Leakage Current I
SHDN
SHDN = GND or IN 1 µA
High-Side Current Limit I
LIMP
300 565 mA
Low-Side Current Limit I
LIMN
200 430 mA
I
LX
= -50mA, V
IN
= 3.0V 1.4
High-Side On-Resistance R
ONP
I
LX
= -50mA, V
IN
= 5.5V 1.1
Ω
I
LX
= -50mA, V
IN
= 3.0V 2
Rectifier On-Resistance R
ONN
I
LX
= -50mA, V
IN
= 5.5V 1.6
Ω
LX Leakage Current I
LXLEAK
V
IN
= 5.5V, V
LX
= 0 to V
IN
5 µA
LX Reverse Leakage Current I
LXLK
,
R
IN unconnected, V
LX
= 5.5V, SHDN = GND 5 µA
Minimum On-Time t
ON
(
MIN
)
0.25 0.55 µs
Minimum Off-Time
t
OFF( M IN)
0.25 0.55 µs
P1-P3P4-P6P7-P8

MAX1733EUK+T

Mfr. #:
Buy MAX1733EUK+T
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators Step-Down Converter
Lifecycle:
New from this manufacturer.
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