POWER LOSS (W)
LTC3411A
1.25A, 4MHz, Synchronous
Step-Down DC/DC Converter
FEATURES DESCRIPTION
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Uses Tiny Capacitors and Inductor
The LTC 3411A is a constant frequency, synchronous
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High Frequency Operation: Up to 4MHz
step-down DC/DC converter. Intended for medium power
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Low R Internal Switches: 0.15
applications, it operates from a 2.5V to 5.5V input voltage
DS(ON)
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High Efficiency: Up to 96%
range and has a user configurable operating frequency up
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Selectable Low Ripple (25mV ) Burst Mode
to 4MHz, allowing the use of tiny, low cost capacitors and
P-P
Operation: I = 40A
inductors 1mm or less in height. The output voltage is
Q
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Stable with Ceramic Capacitors
adjustable from 0.8V to 5.5V. Internal synchronous power
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Current Mode Operation for Excellent Line and Load
switches provide high efficiency. The LTC3411As current
Transient Response
mode architecture and external compensation allow the
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Short-Circuit Protected
transient response to be optimized over a wide range of
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Low Dropout Operation: 100% Duty Cycle
loads and output capacitors.
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Low Shutdown Current: I 1A
Q
The LTC3411A can be configured for automatic power
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Output Voltages from 0.8V to 5V
saving Burst Mode operation (I = 40A) to reduce gate
Q
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Synchronizable to External Clock
charge losses when the load current drops below the level
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Supports Prebiased Outputs
required for continuous operation. For reduced noise and
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Small 10-Lead 3mm 3mm DFN or MSOP Package
RF interference, the SYNC/MODE pin can be configured
to skip pulses or provide forced continuous operation.
APPLICATIONS
To further maximize battery life, the P-channel MOSFET
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Notebook Computers
is turned on continuously in dropout (100% duty cycle).
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Digital Cameras
In shutdown, the device draws <1A.
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Cellular Phones
All registered trademarks and trademarks are the property of their respective owners. Protected
n by U.S. patents, including 5481178, 6580258, 6498466, 6611131..
Handheld Instruments
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Board Mounted Power Supplies
TYPICAL APPLICATION
Efficiency and Power Loss vs Output Current
Step-Down 2.5V/1.25A Regulator
100 1
V
IN
2.5V TO 5.5V
90
80
10F
0.1
70
SYNC SYNC/MODE PV
IN
60
PGOOD SV
IN 2.2H
V
OUT
50 0.01
SW 2.5V
LTC3411A
1.25A
22pF
40
30
0.001
I
22F
TH V = 2.7V
887k 20 IN
V = 3.6V
SHDN/R V
T FB IN
12.1k
10
V = 4.2V
IN
SGND PGND
0 0.0001
549k
412k
680pF
0.1 1 10 100 1000 10000
OUTPUT CURRENT (mA)
3411a TA01a f = 1MHz
O 3411A TA01b
Burst Mode OPERATION
Rev. E
1
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EFFICIENCY (%)LTC3411A
ABSOLUTE MAXIMUM RATINGS (Note 1)
PV , SV Voltages .................................... 0.3V to 6V
Operating Junction Temperature Range
IN IN
V , I , SHDN/R Voltages ......... 0.3V to (V + 0.3V)
(Notes 2, 5, 8) ........................................ 40C to 125C
FB TH T IN
SYNC/MODE Voltage ................... 0.3V to (V + 0.3V)
Storage Temperature Range .................. 65C to 125C
IN
SW Voltage ................................. 0.3V to (V + 0.3V)
Lead Temperature
IN
PGOOD Voltage ............................ 0.3V to (V + 0.3V)
(MS Package Soldering, 10 sec) ...........................300C
IN
PIN CONFIGURATION
TOP VIEW
TOP VIEW
SHDN/R 1 10 I
T TH
SHDN/R 1 10 I
T TH
SYNC/MODE 2 9 V
FB
SYNC/MODE 2 9 V
FB
11
SGND 3 8 PGOOD
SGND 3 8 PGOOD
SW 4 7 SV
SW 4 7 SV
IN
IN
PGND 5 6 PV
IN
PGND 5 6 PV
IN
MS PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
10-LEAD (3mm 3mm) PLASTIC DFN
T = 125C, = 120C/W
JMAX JA
T = 125C, = 43C/W
JMAX JA
EXPOSED PAD (PIN 11) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3411AEDD#PBF LTC3411AEDD#TRPBF LAJM 10-Lead (3mm 3mm) Plastic DFN 40C to 125C
LTC3411AIDD#PBF LTC3411AIDD#TRPBF LAJM 10-Lead (3mm 3mm) Plastic DFN 40C to 125C
LTC3411AEMS#PBF LTC3411AEMS#TRPBF LTAJK 10-Lead Plastic MSOP 40C to 125C
LTC3411AIMS#PBF LTC3411AIMS#TRPBF LTAJK 10-Lead Plastic MSOP 40C to 125C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at T = 25C, V = 3.6V, R = 125k unless otherwise specified. (Note 2)
A IN T
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Operating Voltage Range l 2.5 5.5 V
IN
I Feedback Pin Input Current (Note 3) 0.1 A
FB
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V Feedback Voltage (Note 3) 0.784 0.8 0.816 V
FB
V Reference Voltage Line Regulation V = 2.5V to 5.5V 0.04 0.2 %/V
LINEREG IN
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V Output Voltage Load Regulation I = 0.55V to 0.9V 0.02 0.2 %
LOADREG TH
g Error Amplifier Transconductance I Pin Load = 5A (Note 3) 300 S
m(EA) TH
Rev. E
2
For more information www.analog.com