LTC3530 Datasheet, PDF (1/16 Pages) Linear Technology – Wide Input Voltage Synchronous Buck-Boost DC/DC Converter

FEATURES
n _{Regulated Output with Input Voltages Above, Below}
or Equal to the Output
n _{1.8V to 5.5V Input and 1.8V to 5.25V Output Range}
n _{250mA Continuous Output Current from 1.8V VIN}
n _{600mA Continuous/1A Peak Output Current from}
Li-Ion
n _{Single Inductor}
n _{Synchronous Rectification: Up to 96% Efficiency}
n _{Programmable Automatic Burst Mode}^® _Operation
n _{Output Disconnect in Shutdown}
n _{Pin Compatible with the LTC3440}
n _{Programmable Frequency from 300kHz to 2MHz}
n _{<1μA Shutdown Current}
n _{Small Thermally Enhanced 10-Lead (3mm × 3mm)}
DFN and 10-Lead MS Packages
APPLICATIONS
n _{MP3 Players}
n _{Handheld Instruments}
n _{Digital Cameras}
n _{Smart Phones}
n _{Portable GPS Units}
n _{Miniature Hard Disk Drive Power}
LTC3530
Wide Input Voltage
Synchronous Buck-Boost
DC/DC Converter
DESCRIPTION
The LTC^®3530 is a wide V_IN range, highly efficient, fixed
frequency, buck-boost DC/DC converter that operates
from input voltages above, below or 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 single lithium-ion, two-cell
alkaline or NiMH applications where the output voltage is
within the battery voltage range.
The LTC3530 is pin compatible with the LTC3440 buck-
boost DC/DC converter but adds programmable automatic
Burst Mode operation and extends the V_IN/V_OUT range to
1.8V. Switching frequencies up to 2MHz are programmed
with an external resistor. Automatic Burst Mode operation
allows the user to program the load current threshold for
Burst Mode operation using a single resistor from the
BURST pin to GND.
Other features include 1μA shutdown, short circuit pro-
tection, programmable soft-start control, current limit
and thermal shutdown. The LTC3530 is available in a
thermally enhanced 10-lead (3mm × 3mm) DFN or MSOP
package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patents Pending.
TYPICAL APPLICATION
4.7μH
1.8V TO 5.5V
OFF ON
10μF
33.2k
SW1
SW2
V_OUT
V_IN LTC3530
SHDN/SS
FB
R_T
V_C
BURST
GND
33pF
1M
15k
10k
576k
560pF
0.01μF
100k
V_OUT
3.3V AT
250mA
22μF
3530 TA01a
Efficiency
100
90 ^{Burst Mode VIN = 3.6V}
V_IN = 4.2V
80
V_IN = 3.6V
70
60
50
40
30
20 ^{VIN = 2.0V}
10
0
0.1
1
10
100
1000
LOAD CURRENT (mA)
3350 TA01b
3530fb
1