LTC3442
Micropower Synchronous
Buck-Boost DC/DC Converter with
Automatic Burst Mode Operation
DESCRIPTIO
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FEATURES
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Regulated Output with Input Voltages Above,
Below, or Equal to the Output
Single Inductor, No Schottky Diodes Required
Manual or Programmable Automatic Burst Mode®
Operation
Programmable Average Input Current Limit
Up to 1.2A Continuous Output Current from a Single
Lithium-Ion Cell
High Efficiency: Up to 95%
Output Disconnect in Shutdown
2.4V to 5.5V Input Range
2.4V to 5.25V Output Range
35µA Quiescent Current in Burst Mode Operation
Programmable Frequency from 300kHz to 2MHz
<1µA Shutdown Current
Small, Thermally Enhanced 12-Lead (4mm × 3mm)
DFN Package
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The device includes two 0.10Ω N-channel MOSFET
switches and two 0.10Ω P-channel switches. Operating
frequency and average input current limit can each be
programmed with an external resistor. Quiescent current
is only 35µA in Burst Mode operation, maximizing battery
life in portable applications. Automatic Burst Mode operation allows the user to program the load current for Burst
Mode operation, or to control it manually.
Other features include 1µA shutdown current, programmable soft-start, peak current limit and thermal shutdown.
The LTC3442 is available in a low profile, thermally enhanced 12-lead (4mm × 3mm × 0.75mm) DFN package.
APPLICATIO S
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The LTC®3442 is a highly efficient, fixed frequency, BuckBoost DC/DC converter, which operates from input voltages above, below, and 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 a single Lithium-Ion or multicell alkaline
applications where the output voltage is within the battery
voltage range.
PDA/‘SMART’ Phones
Handheld Computers
MP3 Players
Handheld Instruments
Digital Cameras
Wireless Handsets
USB Peripherals
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode
is a registered trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 6404251, 6166527.
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TYPICAL APPLICATIO
Efficiency vs VIN
4.7µH
100
300mA LOAD
VIN
VIN
2.5V TO
4.2V
SW2
VOUT
1M
340k
LTC3442
SHDN/SS
FB
RLIM
Li-Ion
2.2k
VC
0.01µF
22µF
15k
RT
SGND
1A LOAD
80
70
220pF
470pF
10µF
71.5k
VOUT
3.3V
1.2A
90
EFFICIENCY (%)
SW1
60
VOUT = 3.3V
L = 4.7µH
F = 600kHz
BURST
PGND
0.01µF
200k
50
200k
2.5
3442 TA01a
3.0
3.5
4.0
VIN (V)
4.5
5.0
5.5
3442 • TA01b
3442fa
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