POWER LOSS (W)
LTC3122
15V, 2.5A Synchronous
Step-Up DC/DC Converter
with Output Disconnect
Fea T Descrip T
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V Range: 1.8V to 5.5V, 500mV After Start-Up The LTC 3122 is a synchronous step-up DC/DC converter
IN
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Output Voltage Range: 2.2V to 15V with true output disconnect and inrush current limiting. The
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800mA Output Current for V = 5V and V = 12V 2.5A current limit along with the ability to program output
IN OUT
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Output Disconnects from Input When Shut Down voltages up to 15V makes the LTC3122 well suited for a
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Synchronous Rectification: Up to 95% Efficiency variety of demanding applications. Once started, opera-
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Inrush Current Limit tion will continue with inputs down to 500mV, extending
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Up to 3MHz Adjustable Switching Frequency runtime in many applications.
Synchronizable to External Clock
The LTC3122 features output disconnect in shutdown,
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Selectable Burst Mode Operation: 25A I
Q
dramatically reducing input power drain and enabling
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Output Overvoltage Protection
V to completely discharge. Adjustable PWM switching
OUT
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Soft-Start
from 100kHz to 3MHz optimizes applications for highest
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<1A I in Shutdown
Q
efficiency or smallest solution footprint. The oscillator
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12-Lead, 3mm 4mm 0.75mm Thermally
can also be synchronized to an external clock for noise
Enhanced DFN and MSOP Packages
sensitive applications. Selectable Burst Mode operation
reduces quiescent current to 25A, ensuring high efficiency
a T
across the entire load range. An internal soft-start limits
inrush current during start-up.
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RF Power
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Piezo Actuators
Other features include a <1A shutdown current and ro-
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Small DC Motors
bust protection under short-circuit, thermal overload, and
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12V Analog Rail From Battery, 5V, or Backup Capacitor
output overvoltage conditions. The LTC3122 is offered in
both a low profile 12-lead (3mm 4mm 0.75 mm) DFN
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
package and a 12-lead thermally enhanced MSOP package.
property of their respective owners.
Typical a T
5V to 12V Synchronous Boost Converter with Output Disconnect Efficiency Curve
100 10
3.3H
V
IN
Burst Mode
5V 90
OPERATION
SW 80
V
OUT
V V
12V
IN OUT
70
1
800mA
LTC3122
PWM
SD
OFF ON 100nF 60
4.7F
BURST PWM PWM/SYNC CAP 50
1.02M
40
RT FB
22F
0.1
30
PWM POWER LOSS
V V
113k
CC C
20
SGND PGND 210k
57.6k
10
10pF
4.7F 390pF
0 0.01
0.01 0.1 1 10 100 1000
LOAD CURRENT (mA)
3122 TA01b
3122 TA01a
3122fa
1
For more information www.linear.com/LTC3122
EFFICIENCY (%)
ion pplica
ions pplica
ion uresLTC3122
a Te Maxi Mu M r a T
(Note 1)
V Voltage .................................................. 0.3V to 6V All Other Pins ............................................... 0.3V to 6V
IN
V Voltage ............................................ 0.3V to 18V Operating Junction Temperature Range (Notes 3, 4)
OUT
SW Voltage (Note 2) .................................. 0.3V to 18V LTC3122E/LTC3122I .......................... 40C to 125C
SW Voltage (Pulsed < 100ns) (Note 2) ....... 0.3V to 19V LTC3122H .......................................... 40C to 150C
V , RT Voltage .......................................... 0.3V to V Storage Temperature Range .................. 65C to 150C
C CC
CAP Voltage MSE Lead Temperature (Soldering, 10sec) ...........300C
V < 5.7V ............................0.3V to (V + 0.3V)
OUT OUT
5.7V V 11.7V...... (V 6V) to (V + 0.3V)
OUT OUT OUT
V > 11.7V .................................(V 6V) to 12V
OUT OUT
p in c F T
TOP VIEW
TOP VIEW
SW 1 12 CAP
SW 1 12 CAP
PGND 2 11 V
OUT
PGND 2 11 V
OUT
V 3 10 SGND
IN
13 V 3 13 10 SGND
IN
PGND PGND
PWM/SYNC 4 9 SD
PWM/SYNC 4 9 SD
5
V 8 FB
CC
V 5 8 FB
CC RT 6 7 V
C
RT 6 7 V
C
MSE PACKAGE
12-LEAD PLASTIC MSOP
DE PACKAGE
T = 150C, = 40C/W (NOTE 5), = 10C/W
JMAX JA JC
12-LEAD (4mm 3mm) PLASTIC DFN
EXPOSED PAD (PIN 13) IS PGND,
T = 125C, = 43C/W (NOTE 5), = 5C/W
JMAX JA JC
MUST BE SOLDERED TO PCB FOR RATED THERMAL PERFORMANCE
EXPOSED PAD (PIN 13) IS PGND,
MUST BE SOLDERED TO PCB FOR RATED THERMAL PERFORMANCE
o r Der i n F Ma T
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3122EDE#PBF LTC3122EDE#TRPBF 3122 12-Lead (4mm 3mm) Plastic DFN 40C to 125C
LTC3122IDE#PBF LTC3122IDE#TRPBF 3122 12-Lead (4mm 3mm) Plastic DFN 40C to 125C
LTC3122EMSE#PBF LTC3122EMSE#TRPBF 3122 12-Lead Plastic MSOP 40C to 125C
LTC3122IMSE#PBF LTC3122IMSE#TRPBF 3122 12-Lead Plastic MSOP 40C to 125C
LTC3122HMSE#PBF LTC3122HMSE#TRPBF 3122 12-Lead Plastic MSOP 40C to 150C
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: