LTC3441
1
3441fc
For more information www.linear.com/LTC3441
Typical applicaTion
FeaTures
applicaTions
DescripTion
High Current Micropower
Synchronous Buck-Boost
DC/DC Converter
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.
Li-Ion to 3.3V at 1A Buck-Boost Converter
n
Regulated Output with Input Above, Below or Equal
to the Output
n
Single Inductor, No Schottky Diodes
n
High Efficiency: Up to 95%
n
25µA Quiescent Current in Burst Mode
®
Operation
n
Up to 1.2A Continuous Output Current from a Single
Lithium-Ion
n
True Output Disconnect in Shutdown
n
2.4V to 5.5V Input Range
n
2.4V to 5.25V Output Range
n
1MHz Fixed Frequency Operation
n
Synchronizable Oscillator
n
Selectable Burst Mode or Fixed Frequency Operation
n
<1µA Quiescent Current in Shutdown
n
Small, Thermally Enhanced 12-Lead (4mm × 3mm)
DFN package
n
Handheld Computers
n
Handheld Instruments
n
MP3 Players
n
Digital Cameras
Efficiency vs V
IN
SW1
PV
IN
V
IN
SHDN/SS
MODE/SYNC
PGND
5
8
12
11
2
6
4
9
10
1
7
3
SW2
V
OUT
FB
V
C
GND
PGND
LTC3441
C
IN
10µF
*1 = Burst Mode OPERATION
0 = FIXED FREQUENCY
C
IN
: TAIYO YUDEN JMK212BJ106MG
C
OUT
: TAIYO YUDEN JMK325BJ226MM
L1: TOKO A916CY-4R7M
2.5V TO 4.2V
Li-Ion
*
15k
340k
C
OUT
22µF
V
OUT
3.3V
1A
200k
1.5nF
3441 TA01
L1
4.7µH
V
IN
(V)
2.5
50
EFFICIENCY (%)
60
70
80
3
3.5
4 4.5
3441 TA02
5
90
55
65
75
85
95
5.5
I
OUT
= 200mA
I
OUT
= 1A
V
OUT
= 3.3V
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.