LTC3406B-2 Datasheet, PDF (1/16 Pages) Linear Technology – 2.25MHz, 600mA Synchronous Step-Down Regulator in ThinSOT

FEATURES
■ _{High Efficiency: Up to 96%}
■ _{600mA Output Current at VIN = 3V}
■ _{2.5V to 5.5V Input Voltage Range}
■ _{2.25MHz Constant Frequency Operation}
■ _{No Schottky Diode Required}
■ _{Low Dropout Operation: 100% Duty Cycle}
■ _{Low Quiescent Current: 350µA}
■ _{0.6V Reference Allows Low Output Voltages}
■ _{Shutdown Mode Draws < 1µA Supply Current}
■ _{Current Mode Operation for Excellent Line and}
Load Transient Response
■ _{Overtemperature Protected}
■ _{Low Profile (1mm) SOT-23 Package}
U
APPLICATIO S
■ _{Cellular Telephones}
■ _{Personal Information Appliances}
■ _{Wireless and DSL Modems}
■ _{Digital Still Cameras}
■ _{MP3 Players}
■ _{Portable Instruments}
LTC3406B-2
2.25MHz, 600mA
Synchronous Step-Down
Regulator in ThinSOT^TM
DESCRIPTIO
The LTC^®3406B-2 is a high efficiency monolithic synchro-
nous buck regulator using a constant frequency, current
mode architecture. Supply current with no load is 350µA,
dropping to <1µA in shutdown. The 2.5V to 5.5V input
voltage range makes the LTC3406B-2 ideally suited for
single Li-Ion battery-powered applications. 100% duty
cycle capability provides low dropout operation, extend-
ing battery life in portable systems. PWM pulse skipping
mode operation provides very low output ripple voltage for
noise sensitive applications.
The switching frequency is internally set at 2.25MHz, allow-
ing the use of tiny surface mount inductors and capacitors.
The internal synchronous switch increases efficiency and
eliminates the need for an external Schottky diode. Low
output voltages are easily supported with the 0.6V feedback
reference voltage. The LTC3406B-2 is available in a low pro-
file (1mm) SOT-23 package. Refer to LTC3406 for appli-
cations that require Burst Mode^® operation.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
Protected by U.S. Patents, including 6580258, 5481178.
TYPICAL APPLICATIO
V_IN
2.7V
TO 5.5V
High Efficiency Step-Down Converter
4.7µF
CER
V_IN
SW
LTC3406B-2
RUN
V_FB
GND
2.2µH*
22pF
1M
10µF
CER
V_OUT
1.8V
600mA
499k
3406B TA01a
Efficiency vs Load Current
100
V_OUT = 1.8V
90 ^TA ^{= 25°C}
80
70
60
V_IN = 3.6V
50
V_IN = 2.7V
40
30
20
10
0.1
V_IN = 4.2V
1
10
100
OUTPUT CURRENT (mA)
1000
3406B TA01b
sn3406b2 3406b2fs
1