LTC3411A
1.25A, 4MHz, Synchronous
Step-Down DC/DC Converter
FEATURES
nn Uses Tiny Capacitors and Inductor
nn High Frequency Operation: Up to 4MHz
nn Low RDS(ON) Internal Switches: 0.15Ω
nn High Efficiency: Up to 96%
nn Selectable Low Ripple (25mVP-P) Burst Mode®
Operation: IQ = 40µA
nn Stable with Ceramic Capacitors
nn Current Mode Operation for Excellent Line and Load
Transient Response
nn Short-Circuit Protected
nn Low Dropout Operation: 100% Duty Cycle
nn Low Shutdown Current: IQ ≤ 1µA
nn Output Voltages from 0.8V to 5V
nn Synchronizable to External Clock
nn Supports Prebiased Outputs
nn Small 10-Lead 3mm × 3mm DFN or MSOP Package
APPLICATIONS
nn Notebook Computers
nn Digital Cameras
nn Cellular Phones
nn Handheld Instruments
nn Board Mounted Power Supplies
DESCRIPTION
The LTC®3411A is a constant frequency, synchronous
step-down DC/DC converter. Intended for medium power
applications, it operates from a 2.5V to 5.5V input voltage
range and has a user configurable operating frequency up
to 4MHz, allowing the use of tiny, low cost capacitors and
inductors 1mm or less in height. The output voltage is
adjustable from 0.8V to 5.5V. Internal synchronous power
switches provide high efficiency. The LTC3411A’s current
mode architecture and external compensation allow the
transient response to be optimized over a wide range of
loads and output capacitors.
The LTC3411A can be configured for automatic power
saving Burst Mode operation (IQ = 40µA) to reduce gate
charge losses when the load current drops below the level
required for continuous operation. For reduced noise and
RF interference, the SYNC/MODE pin can be configured
to skip pulses or provide forced continuous operation.
To further maximize battery life, the P-channel MOSFET
is turned on continuously in dropout (100% duty cycle).
In shutdown, the device draws <1µA.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. patents, including 5481178, 6580258, 6498466, 6611131..
TYPICAL APPLICATION
Step-Down 2.5V/1.25A Regulator
VIN
2.5V TO 5.5V
SYNC
SYNC/MODE
PVIN
PGOOD
SVIN
SW
LTC3411A
10µF
2.2µH
22pF
VOUT
2.5V
1.25A
12.1k
680pF
ITH
SHDN/RT
SGND
549k
VFB
PGND
887k
412k
22µF
3411a TA01a
Efficiency and Power Loss vs Output Current
100
1
90
80
0.1
70
60
50
0.01
40
30
0.001
20
VIN = 2.7V
VIN = 3.6V
10
VIN = 4.2V
0
0.0001
0.1
1
10
100 1000 10000
OUTPUT CURRENT (mA)
fO = 1MHz
Burst Mode OPERATION
3411A TA01b
Document Feedback
For more information www.analog.com
Rev. E
1
