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 range of 2.7V to 15V, the LTC3112 is well-
suited for a wide variety of single or multiple cell battery,
backup capacitor or wall adapter source applications. Low
R
DS(ON)
internal N-Channel MOSFET switches provide
highly efficient operation in applications with higher load
current requirements.
The LTC3112 features selectable PWM or Burst Mode
operation, an easily synchronized oscillator and output
disconnect in shutdown. An output current monitor circuit
allows the load current to be controlled or measured. Other
features include <1µA shutdown current, short circuit
protection, soft-start, current limit and thermal shutdown.
The LTC3112 is offered in both a 16-pin (4mm
×
5mm
×
0.75mm) DFN and 20-pin TSSOP packages.
L,
LT, LTC, LTM, Linear Technology Burst Mode, LTSpice and the Linear logo are registered
trademarks and No R
SENSE
and PowerPath are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 5481178.
n
n
n
n
n
n
n
n
n
n
Regulated Output with V
IN
Above, Below or Equal to V
OUT
2.7V to 15V Input Voltage Range
2.5V to 14V Output Voltage Range
2.5A Continuous Output Current: V
IN
≥ 5V,
V
OUT
= 5V, PWM Mode
Output Current Monitor
Up to 95% Efficiency
750kHz Switching Frequency, Synchronizable
Between 300kHz and 1.5MHz
Internal N-Channel MOSFETs
Selectable Burst Mode
®
Operation, I
Q
= 50µA
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
applicaTions
n
n
n
n
n
n
n
3.3V or 5V from 1, 2 or 3 Li-Ion, Backup Capacitor Stack
Hand Held Inventory Terminals
RF Transmitters
12V Synchronous Boost Converter
Multiple Power Input Systems
LED Lighting with Current Regulation
12V Lead Acid Battery to 12V
Typical applicaTion
5V, 750kHz Wide Input Voltage Range Buck-Boost Regulator
4.7µH
EFFICIENCY (%)
0.1µF
V
IN
2.7V TO 15V
SW1
BST1
V
IN
V
CC
BURST PWM
10µF
OFF ON
1µF
PWM/SYNC
RUN
GND
SW2
BST2
V
OUT
LTC3112 COMP
FB
0.1µF
5V/2.5A, V
IN
> 5V
V
OUT
47pF
10k
47µF
158k
3112 TA01
Efficiency at 5V
OUT
100
90
80
70
60
50
40
30
0.0001
0.001
0.01
0.1
LOAD CURRENT (A)
1
3112 TA02
PWM
BURST
680pF 33k
845k
22pF
TO ADC
1V PER AMP
42.2k
I
OUT
OVP
100pF
2.7V
IN
5.0V
IN
12V
IN
3112fc
For more information
www.linear.com/LTC3112
1
LTC3112
absoluTe MaxiMuM raTings
(Notes 1, 3)
V
IN
Voltage ................................................. – 0.3V to 16V
V
OUT
Voltage .............................................. – 0.3V to 15V
SW1 Voltage (Note 4) ................... – 0.3V to (V
IN
+ 0.3V)
SW2 Voltage (Note 4) ................ – 0.3V to (V
OUT
+ 0.3V)
V
BST1
Voltage................... (V
SW1
– 0.3V) to (V
SW1
+ 6V)
V
BST2
Voltage...................(V
SW2
– 0.3V) to (V
SW2
+ 6V)
RUN Voltage............................................... – 0.3V to 16V
PWM/SYNC, V
CC
, I
OUT
Voltage ....................– 0.3V to 6V
FB, COMP, OVP Voltage ...............................– 0.3V to 6V
Operating Junction Temperature Range (Notes 2, 6)
............................................................... –55°C to 150°C
Storage Temperature Range ..................– 65°C to 150°C
Lead Temperature (Soldering, 10sec) TSSOP ....... 300°C
pin conFiguraTion
TOP VIEW
TOP VIEW
COMP
FB
OVP
V
IN
V
IN
RUN
I
OUT
V
OUT
1
2
3
4
5
6
7
8
17
GND
16 PWM/SYNC
15 V
CC
14 BST1
13 SW1
12 SW1
11 BST2
10 SW2
9
SW2
GND
COMP
FB
OVP
V
IN
V
IN
RUN
I
OUT
V
OUT
1
2
3
4
5
6
7
8
9
21
GND
20 GND
19 PWM/SYNC
18 V
CC
17 BST1
16 SW1
15 SW1
14 BST2
13 SW2
12 SW2
11 GND
DHD16 PACKAGE
16-LEAD (5mm
×
4mm) PLASTIC DFN
T
JMAX
=150 °C,
q
JA
= 43°C/W,
q
JC
= 4°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
GND 10
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 150°C,
q
JA
= 38°C/W,
q
JC
= 4°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3112EDHD#PBF
LTC3112IDHD#PBF
LTC3112HDHD#PBF
LTC3112MPDHD#PBF
LTC3112EFE#PBF
LTC3112IFE#PBF
LTC3112HFE#PBF
LTC3112MPFE#PBF
TAPE AND REEL
LTC3112EDHD#TRPBF
LTC3112IDHD#TRPBF
LTC3112HDHD#TRPBF
LTC3112MPDHD#TRPBF
LTC3112EFE#TRPBF
LTC3112IFE#TRPBF
LTC3112HFE#TRPBF
LTC3112MPFE#TRPBF
PART MARKING*
3112
3112
3112
3112
3112FE
3112FE
3112FE
3112FE
PACKAGE DESCRIPTION
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
16-Lead (5mm
×
4mm) Plastic DFN
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3112fc
2
For more information
www.linear.com/LTC3112
LTC3112
elecTrical characTerisTics
PARAMETER
Input Operating Range
V
IN
UVLO Threshold
V
IN
UVLO Hysteresis
V
CC
UVLO Threshold
V
CC
UVLO Hysteresis
Output Voltage Adjust Range
INTV
CC
Clamp Voltage
V
CC
Voltage in Dropout
Quiescent Current – Burst Mode Operation
Quiescent Current – Shutdown
Feedback Voltage = PWM Mode Operation
Feedback Leakage
OVP Threshold
OVP Hysteresis
OVP Leakage
NMOS Switch Leakage
NMOS Switch On Resistance
NMOS Switch On Resistance
NMOS Switch On Resistance
Input Current Limit
Peak Current Limit
Burst Current Limit
Burst Zero Current Threshold
Reverse Current Limit
I
OUT
Accuracy (Note 5)
Maximum Duty Cycle
Minimum Duty Cycle
Frequency
SYNC Frequency Range (Note 7)
PWM/SYNC Threshold
RUN Threshold
V
CC
= 2.7V or 5V
V
IN
= 2.7V or 15V
V
FB
= 0.8V
Rising Threshold
Measured at OVP Pin
OVP = 0.8V
Switch A, B, C, D, V
IN
= V
OUT
= 12V
Switch A
Switch B, C
Switch D
L = 4.7µH
L = 4.7µH
L = 4.7µH
L = 4.7µH
L = 4.7µH
SW2 to V
OUT
Current = 1.5A
SW2 to V
OUT
Current = 1.0A
SW2 to V
OUT
Current = 0.5A
Buck (Switch A On)
Boost (Switch C On)
Buck (Switch A On)
Boost (Switch C On)
PWM/SYNC = 5V, V
IN
= V
OUT
= 12V
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= V
OUT
= PWM/SYNC = RUN = 5V unless otherwise noted.
CONDITIONS
0°C to 150°C
–55°C to 0°C
Rising
Rising
l
MIN
2.7
2.85
2.0
2.2
2.5
3.8
TYP
MAX
15
15
UNITS
V
V
V
mV
V
mV
V
V
V
µA
µA
V
nA
V
mV
nA
µA
mΩ
mΩ
mΩ
2.3
300
2.35
150
2.7
2.5
14
V
IN
= 5V or 15V
V
IN
= 2.7V, I
VCC
= 10mA
V
FB
= 1V, V
PWM/SYNC
= 0V
RUN = V
OUT
= V
CC
= 0V, Not Including Switch Leakage
l
4.2
2.6
50
0
4.6
75
1
0.818
50
0.88
100
10
l
0.778
0.78
0.8
0
0.83
20
0
1
40
50
60
4.5
7
0.7
–0.5
32
20
8
80
75
5
675
300
0.5
0.35
6
10
1.3
0.3
–1
36
24
12
87
82
8.5
12
2
–1.5
40
28
16
A
A
A
A
A
µA
µA
µA
%
%
0
12
750
0.9
0.75
825
1500
1.5
1.5
%
%
kHz
kHz
V
V
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings may
cause permanent damage to the device. Exposure to any Absolute Maximum
Rating condition for extended periods may affect device reliability and lifetime.
Note 2:
The LTC3112 is tested under pulsed load conditions such that T
J
≈ T
A
.
The LTC3112E is guaranteed to meet specifications from 0°C to 85°C junction
temperature. Specifications over the –40°C to 125°C operating junction
temperature range are assured by design, characterization and correlation with
statistical process controls. The LTC3112I is guaranteed to meet specifications
over the –40°C to 125°C operating junction temperature, the LTC3112H is
guaranteed to meet specifications over the –40°C to 150°C operating junction
temperature range and the LTC3112MP is guaranteed and tested to meet
specifications over the full –55°C to 150°C operating junction temperature
range. High junction temperatures degrade operating lifetimes; operating
lifetime is derated for temperature greater than 125°C. Note that the maximum
ambient temperature consistent with these specifications is determined by
specific operating conditions in conjunction with board layout, the rated
package thermal impedance and other environmental factors.
3112fc
For more information
www.linear.com/LTC3112
3
LTC3112
elecTrical characTerisTics
Note 3:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 4:
Voltage transients on the switch pins beyond the DC limit specified
in the Absolute Maximum Ratings, are non disruptive to normal operation
when using good layout practices, as shown on the demo board or
described in the data sheet and application notes.
Note 5:
I
OUT
current is tested in a non-switching DC state. In a switching
environment I
OUT
accuracy may exhibit variation with factors such as
switching frequency, load current, input/output voltage, and temperature.
See typical performance characteristic curves for predicted variation.
Note 6:
The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according to
the formula:
T
J
= T
A
+ (P
D
•
q
JA
), where
q
JA
(in °C/W) is the package thermal
impedance.
Note 7:
SYNC frequency range is tested with a square wave. Operation
with 100ns minimum high or low times is assured by design.
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