FEATURES
n Regulated Output with VIN Above, Below
or Equal to VOUT
n 2.5V to 15V Input and Output Voltage Range
n 1.5A Continuous Output Current: VIN ≥ 5V,
VOUT = 5V, PWM Mode
n Single Inductor
n Accurate RUN Threshold
n Up to 95% Efficiency
n 800kHz Switching Frequency, Synchronizable
Between 600kHz and 1.5MHz
n 49µA No-Load Quiescent Current in Burst Mode®
Operation
n Output Disconnect in Shutdown
n Shutdown Current < 1µA
n Internal Soft-Start
n Small, Thermally Enhanced 14-Lead (3mm × 4mm ×
0.75mm) DFN and 16-Lead MSOP Packages
APPLICATIONS
n 3.3V or 5V from 1, 2 or 3 Li-Ion, Multiple-Cell
Alkaline/NiMH Batteries
n RF Transmitters
n Military, Industrial Power Systems
LTC3111
15V, 1.5A Synchronous
Buck-Boost DC/DC
Converter
DESCRIPTION
The LTC®3111 is a fixed frequency, synchronous buck-
boost DC/DC converter with an extended input and output
range. The unique 4-switch, single inductor architecture
provides low noise and seamless operation from input
voltages above, below or equal to the output voltage.
With an input and output range of 2.5V to 15V, the LTC3111
is well suited for a wide variety of single or multiple-cell
batteries, back-up capacitor or wall adapter source applica-
tions. Low RDS(ON) internal N-channel MOSFET switches
and selectable PWM or Burst Mode operation produce
high efficiency over a wide range of operating conditions.
An accurate RUN pin allows the user to program the
turn-on threshold voltage of the converter. Other features
include: short-circuit protection, internal soft-start and
thermal shutdown.
The LTC3111 is offered in both thermally enhanced
14-lead (3mm × 4mm × 0.75mm) DFN and 16-lead MSOP
packages.
L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, LTspice are registered
trademarks and No RSENSE and PowerPath are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 6404251, 6166527, 5481178, 6304066, 6580258.
TYPICAL APPLICATION
5V, 800kHz Wide Input Voltage Buck-Boost Regulator
4.7µH
0.1µF
VIN
2.5V TO 15V
10µF
SW1
BST1
VIN
SW2
BST2
VOUT
LTC3111
COMP
BURST PWM
PWM/SYNC
OFF ON
RUN
FB
SNSGND
SGND
VCC
PGND
0.1µF
680pF
26.1k
27pF
1µF
20k
1M
VOUT
5V
1.5A
22µF (VIN > 5V)
33pF
191k
3111 TA01a
For more information www.linear.com/LTC3111
Efficiency at 5VOUT
100
PWM
90
BURST
80
70
60
50
40
30
0.0001
VIN = 2.7V
VIN = 5V
VIN = 12V
0.001 0.01 0.1
LOAD CURRENT (A)
1
10
3111 TA01b
3111fa
1
