LTC3531/
LTC3531-3.3/LTC3531-3
200mA Buck-Boost
Synchronous DC/DC
Converters
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FEATURES
DESCRIPTIO
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Regulated Output with Input Above, Below or Equal
The LTC®3531/LTC3531-3.3/LTC3531-3 are synchronous
buck-boost DC/DC converters that operate from input
voltages above, below or equal to the output voltage. The
topology incorporated in the ICs provides a continuous
transfer through all operating modes, making the product
ideal for single cell Li-Ion and multicell alkaline or nickel
applications. The converters operate in Burst Mode, mini-
mizing solution footprint and component count as well as
providing high conversion efficiency over a wide range of
load currents.
to the Output
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Single Inductor
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Up to 90% Efficiency
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V Range: 1.8V to 5.5V
IN
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200mA at 3.3V
from 3.6V Input
OUT
125mA at 3V
from 2.5V Input
OUT
Fixed V
Versions (TSOT, DFN): 3.3V, 3V
OUT
Adjustable V
Version (DFN): 2V to 5V
OUT
Burst Mode® Operation, No External Compensation
Ultra Low Quiescent Current: 16μA, Shutdown
Current <1μA
Thedevicesincludetwo0.5ΩN-channelMOSFETswitches
and two P-channel switches (0.5Ω, 0.8Ω). Quiescent
current is typically 16μA, making the parts ideal for bat-
tery power applications. Other features include a <1μA
shutdown current, current limiting, thermal shutdown
and output disconnect. The parts are offered in a 6-pin
ThinSOTTM package for fixed voltage versions or a 3mm ×
3mm DFN package for fixed and adjustable versions.
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Only 3 External Components Required
(Fixed Voltage Versions)
Short-Circuit Protection
Output Disconnect in Shutdown
Available in 6-Pin ThinSOT and 3mm × 3mm DFN
Packages
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APPLICATIO S
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6166527.
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Handheld Instruments
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MP3 Players
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Handheld computers
PDA/GPS
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TYPICAL APPLICATIO
Efficiency vs VIN
100
10μH
95
90
85
80
75
70
65
60
BOOST
MODE
SW1
SW2
V
V
IN
OUT
BUCK
MODE
3.1V TO
4.2V
V
V
3.3V
IN
OUT
160mA
LTC3531-3.3
4SW
+
Li-Ion
2.2μF
10μF
MODE
SHDN
GND
3531 TA01a
ON OFF
3.3V
4
AT 100mA
OUT
3.5
1.5
2
2.5
3
4.5
5
5.5
INPUT VOLTAGE (V)
3531 TA01b
3531fb
1