LTC3443 Datasheet, PDF (1/16 Pages) Linear Technology – High Current Micropower 600kHz Synchronous Buck-Boost DC/DC Converter

LTC3443
High Current Micropower
600kHz Synchronous Buck-Boost
DC/DC Converter
FEATURES
■ _{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
U
APPLICATIO S
■ _{Handheld Computers}
■ _{Handheld Instruments}
■ _{MP3 Players}
■ _{Digital Cameras}
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
U.S. Patent #’s 6404251, 6166527
DESCRIPTIO
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.
TYPICAL APPLICATIO
V_IN
2.5V
TO 4.2V
Li-Ion
Li-Ion to 3.3V at 1A Buck-Boost Converter
6µH
10µF
SW1
SW2
PV_IN
V_OUT
LTC3443
V_IN
FB
SHDN/SS
V_C
MODE/SYNC GND
PGND
PGND
220pF
340k
2.2k
15k
560pF
200k
V_OUT
3.3V
1A
44µF
(2 × 22µF)
3443 TA01
Efficiency vs V_IN
100
I_OUT = 200mA
95
90
85
I_OUT = 1A
80
75
70
65
60
55
V_OUT = 3.3V
50
2.7 3.2 3.7 4.2 4.7
V_IN (V)
5.2
3443 TA02
sn3443 3443fs
1