LTC3442 Datasheet, PDF (1/20 Pages) Linear Integrated Systems – Micropower Synchronous Buck-Boost DC/DC Converter with Automatic Burst Mode Operation

LTC3442
Micropower Synchronous
Buck-Boost DC/DC Converter with
Automatic Burst Mode Operation
FEATURES
DESCRIPTIO
■ _{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
U
APPLICATIO S
■ _{PDA/‘SMART’ Phones}
■ _{Handheld Computers}
■ _{MP3 Players}
■ _{Handheld Instruments}
■ _{Digital Cameras}
■ _{Wireless Handsets}
■ _{USB Peripherals}
The LTC^®3442 is a highly efficient, fixed frequency, Buck-
Boost DC/DC converter, which operates from input volt-
ages 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.
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 opera-
tion allows the user to program the load current for Burst
Mode operation, or to control it manually.
Other features include 1µA shutdown current, program-
mable soft-start, peak current limit and thermal shutdown.
The LTC3442 is available in a low profile, thermally en-
hanced 12-lead (4mm × 3mm × 0.75mm) DFN package.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Burst Mode is a registered
trademark of Linear Technology Corporation. Protected by U.S. Patents including 6404251,
6166527.
TYPICAL APPLICATIO
4.7µH
V_IN
2.5V TO
4.2V
Li-Ion
10µF
1M
0.01µF
71.5k
SW1
SW2
V_IN
V_OUT
LTC3442
SHDN/SS
FB
R_LIM
V_C
R_T
SGND
BURST
PGND
340k
2.2k
V_OUT
3.3V
1.2A
15k
470pF
220pF
22µF
0.01µF
200k
200k
3442 TA01a
Efficiency vs V_IN
100
300mA LOAD
90
1A LOAD
80
70
60
V_OUT = 3.3V
L = 4.7µH
F = 600kHz
50
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V_IN (V)
3442 • TA01b
3442f
1