LTC3442
Micropower Synchronous
Buck-Boost DC/DC Converter with
Automatic Burst Mode Operation
DESCRIPTIO
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.
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
■
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
APPLICATIO S
■
■
■
■
■
■
■
PDA/‘SMART’ Phones
Handheld Computers
MP3 Players
Handheld Instruments
Digital Cameras
Wireless Handsets
USB Peripherals
TYPICAL APPLICATIO
4.7µH
V
IN
2.5V TO
4.2V
SW1
V
IN
1M
100
300mA LOAD
SW2
V
OUT
V
OUT
3.3V
1.2A
90
EFFICIENCY (%)
LTC3442
SHDN/SS
FB
15k
R
LIM
V
C
340k
2.2k
80
Li-Ion
0.01µF
22µF
470pF
220pF
70
10µF
R
T
71.5k
SGND
BURST
PGND
60
0.01µF
200k
200k
50
2.5
3442 TA01a
U
U
U
Efficiency vs V
IN
1A LOAD
V
OUT
= 3.3V
L = 4.7µH
F = 600kHz
3.0
3.5
4.0
V
IN
(V)
4.5
5.0
5.5
3442 • TA01b
3442f
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
