LTC3112
15V, 2.5A Synchronous
Buck-Boost DC/DC
Converter
FEATURES
DESCRIPTION
TheLTC®3112isafixedfrequencysynchronousbuck-boost
DC/DC converterwith an extended input and output range.
Theunique4-switch,singleinductorarchitectureprovides
low noise and seamless operation from input voltages
above, below or equal to the output voltage.
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Regulated Output with V Above, Below or Equal to V
IN
OUT
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2.7V to 15V Input Voltage Range
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2.5V to 14V Output Voltage Range
2.5A Continuous Output Current: V ≥ 5V,
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IN
V
= 5V, PWM Mode
OUT
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Output Current Monitor
With an input range of 2.7V to 15V, the LTC3112 is well-
suited for a wide variety of single or multiple cell battery,
backup capacitororwall adaptersourceapplications. Low
Up to 95% Efficiency
750kHz Switching Frequency, Synchronizable
Between 300kHz and 1.5MHz
Internal N-Channel MOSFETs
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internal N-Channel MOSFET switches provide
DS(ON)
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highly efficient operation in applications with higher load
Selectable Burst Mode® Operation, I = 50µA
Q
current requirements.
Shutdown Current < 1µA
Overvoltage Protection
Output Disconnect in Shutdown
Internal Soft-Start
Small, Thermally Enhanced 16-Lead (4mm × 5mm ×
0.75mm) DFN and 20-Lead TSSOP Package
The LTC3112 features selectable PWM or Burst Mode
operation, an easily synchronized oscillator and output
disconnectinshutdown. Anoutputcurrentmonitorcircuit
allowstheloadcurrenttobecontrolledormeasured.Other
features include <1µA shutdown current, short circuit
protection, soft-start, currentlimitandthermalshutdown.
APPLICATIONS
The LTC3112 is offered in both a 16-pin (4mm × 5mm ×
0.75mm) DFN and 20-pin TSSOP packages.
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3.3V or 5V from 1, 2 or 3 Li-Ion, Backup Capacitor Stack
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Hand Held Inventory Terminals
L, LT, LTC, LTM, Linear Technology Burst Mode, LTSpice and the Linear logo are registered
trademarks and No R
and PowerPath are trademarks of Linear Technology Corporation.
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SENSE
RF Transmitters
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 5481178.
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12V Synchronous Boost Converter
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Multiple Power Input Systems
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LED Lighting with Current Regulation
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12V Lead Acid Battery to 12V
TYPICAL APPLICATION
Efficiency at 5VOUT
100
5V, 750kHz Wide Input Voltage Range Buck-Boost Regulator
PWM
90
4.7µH
BURST
80
70
0.1µF
0.1µF
SW1
SW2
BST1
BST2
5V/2.5A, V > 5V
IN
2.7V TO 15V
10µF
V
V
OUT
V
OUT
V
IN
IN
33k
60
680pF
47pF
LTC3112
V
COMP
CC
845k
10k
22pF
BURST PWM
OFF ON
PWM/SYNC
50
40
FB
OUT
TO ADC
1V PER AMP
100pF 42.2k
RUN
GND
I
2.7V
5.0V
12V
IN
IN
47µF
OVP
1µF
158k
IN
30
0.0001 0.001
0.01
0.1
1
3112 TA01
LOAD CURRENT (A)
3112 TA02
3112fd
1
For more information www.linear.com/LTC3112