LTC3443
1
3443fa
■
Regulated Output with Input Above, Below or Equal
to the Output
■
Single Inductor, No Schottky Diodes
■
High Efficiency: Up to 96%
■
28μA 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
■
600kHz Fixed Frequency Operation
■
Synchronizable Oscillator
■
Selectable Burst Mode or Fixed Frequency Operation
■
<1μA Quiescent Current in Shutdown
■
Small, Thermally Enhanced 12-Lead
(4mm × 3mm × 0.8mm) DFN package
High Current Micropower
600kHz Synchronous Buck-Boost
DC/DC Converter
■
Handheld Computers
■
Handheld Instruments
■
MP3 Players
■
Digital Cameras
Efficiency vs V
IN
The LTC
®
3443 is a high efficiency, fixed frequency, buck-
boost DC/DC converter that operates from input voltages
above, below or equal to the output voltage. The part is pin
for pin compatible with its predecessor, the LTC3441, with
a lower operating frequency (600kHz), and a V
C
pin clamp
circuit during Burst Mode operation. The topology incor-
porated in the IC provides a continuous transfer function
through all operating modes, making the product ideal for
single Lithium Ion or multicell applications where the out-
put 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 600kHz and can be synchronized up to
1.2MHz. Quiescent current is only 28μA 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 LTC3443 is
available in a thermally enhanced 12-lead (4mm × 3mm)
DFN Package.
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
Li-Ion to 3.3V at 1A Buck-Boost Converter
SW1
PV
IN
V
IN
SHDN/SS
MODE/SYNC
PGND
SW2
V
OUT
FB
V
C
GND
PGND
LTC3443
10μF
V
IN
2.5V
TO 4.2V
Li-Ion
15k
340k
44μF
(2 × 22μF)
V
OUT
3.3V
1A
200k
560pF
3443 TA01
6μH
2.2k
220pF
V
IN
(V)
2.7
50
EFFICIENCY (%)
60
70
80
3.2
3.7
4.2 4.7
3443 TA02
90
100
55
65
75
85
95
5.2
I
OUT
= 1A
I
OUT
= 200mA
V
OUT
= 3.3V
Burst Mode is a registered trademark of Linear Technology Corporation.
U.S. Patent #’s 6404251, 6166527
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
