Features
nn Regulated Output with Input Above, Below or Equal
to the Output
nn Single Inductor, No Schottky Diodes
nn High Efficiency: Up to 95%
nn 25µA Quiescent Current in Burst Mode® Operation
nn Up to 1.2A Continuous Output Current from a Single
Lithium-Ion
nn True Output Disconnect in Shutdown
nn 2.4V to 5.5V Input Range
nn 2.4V to 5.25V Output Range
nn 1MHz Fixed Frequency Operation
nn Synchronizable Oscillator
nn Selectable Burst Mode or Fixed Frequency Operation
nn <1µA Quiescent Current in Shutdown
nn Small, Thermally Enhanced 12-Lead (4mm × 3mm)
DFN package
Applications
nn Handheld Computers
nn Handheld Instruments
nn MP3 Players
nn Digital Cameras
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
LTC3441
High Current Micropower
Synchronous Buck-Boost
DC/DC Converter
Description
The LTC®3441 is a high efficiency, fixed frequency, buck-
boost DC/DC converter that operates efficiently from input
voltages above, below or equal to the output voltage. The
topology incorporated in the IC provides a continuous
transfer function through all operating modes, making
the product ideal for single lithium ion or multicell ap-
plications where the output voltage is within the battery
voltage range.
The device includes two 0.10Ω N-channel MOSFET
switches and two 0.11Ω P-channel switches. External
Schottky diodes are optional, and can be used for a mod-
erate efficiency improvement. The operating frequency
is internally set to 1MHz and can be synchronized up to
1.7MHz. Quiescent current is only 25µA in Burst Mode
operation, maximizing battery life in portable applica-
tions. Burst Mode operation is user controlled and can
be enabled by driving the MODE/SYNC pin high. If the
MODE/SYNC pin is driven low or with a clock, then fixed
frequency switching is enabled.
Other features include a 1µA shutdown, soft-start control,
thermal shutdown and current limit. The LTC3441 is
available in a thermally enhanced 12-lead (4mm × 3mm)
DFN package.
Typical Application
Li-Ion to 3.3V at 1A Buck-Boost Converter
L1
4.7µH
4
SW1
5
SW2
9
8
2.5V TO 4.2V
PVIN
VOUT
10 VIN LTC3441 FB 12
1
11
15k
SHDN/SS
VC
Li-Ion
*
7
2
MODE/SYNC GND
CIN 3
6
1.5nF
10µF
PGND
PGND
340k
VOUT
3.3V
1A
COUT
22µF
200k
*1 = Burst Mode OPERATION
0 = FIXED FREQUENCY
CIN: TAIYO YUDEN JMK212BJ106MG
COUT: TAIYO YUDEN JMK325BJ226MM
L1: TOKO A916CY-4R7M
3441 TA01
Efficiency vs VIN
100 VOUT = 3.3V
95
IOUT = 200mA
90
85
IOUT = 1A
80
75
70
65
60
55
50
2.5 3 3.5 4 4.5 5 5.5
VIN (V)
3441 TA02
For more information www.linear.com/LTC3441
3441fc
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