LTC3441
High Current Micropower
Synchronous Buck-Boost
DC/DC Converter
FEATURES
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DESCRIPTIO
Regulated Output with Input Above, Below or Equal
to the Output
Single Inductor, No Schottky Diodes
High Efficiency: Up to 95%
25μA Quiescent Current in Burst Mode
®
Operation
Up to 1.2A Continuous Output Current from a Single
Lithium-Ion
True Output Disconnect in Shutdown
2.4V to 5.5V Input Range
2.4V to 5.25V Output Range
1MHz Fixed Frequency Operation
Synchronizable Oscillator
Selectable Burst Mode or Fixed Frequency Operation
<1μA Quiescent Current in Shutdown
Small, Thermally Enhanced 12-Lead (4mm
×
3mm)
DFN package
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 trans-
fer function through all operating modes, making the prod-
uct ideal for single lithium ion or multicell applications 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
moderate 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 applications.
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 fre-
quency 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.
APPLICATIO S
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Handheld Computers
Handheld Instruments
MP3 Players
Digital Cameras
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
L1
4.7μH
4
9
2.5V TO 4.2V
10
5
8
Li-Ion to 3.3V at 1A Buck-Boost Converter
V
OUT
3.3V
1A
340k
EFFICIENCY (%)
100
95
90
85
80
75
70
65
V
OUT
= 3.3V
SW1
PV
IN
SW2
Li-Ion
*
C
IN
10μF
V
OUT
12
LTC3441
V
IN
FB
1
11
V
C
SHDN/SS
7
2
MODE/SYNC GND
3
6
PGND
PGND
15k
1.5nF
200k
C
OUT
22μF
60
55
50
2.5
3
3.5
4
V
IN
(V)
4.5
5
5.5
3441 TA02
*1 = Burst Mode OPERATION
0 = FIXED FREQUENCY
C
IN
: TAIYO YUDEN JMK212BJ106MG
C
OUT
: TAIYO YUDEN JMK325BJ226MM
L1: TOKO A916CY-4R7M
3441 TA01
U
Efficiency vs V
IN
I
OUT
= 200mA
I
OUT
= 1A
3441fa
U
U
1
LINER [ LINEAR TECHNOLOGY ]
