LTC3405A-1.375_15 Datasheet, PDF (1/12 Pages) Linear Technology – 1.375V, 1.5MHz, 300mA Synchronous Step-Down Regulators in ThinSOT

LTC3405A-1.375
1.375V, 1.5MHz, 300mA
Synchronous Step-Down
Regulators in ThinSOT
FEATURES
■ _{High Efficiency: Up to 90%}
■ _{Very Low Quiescent Current: Only 20µA}
During Operation
■ _{300mA Output Current at VIN = 3V}
■ _{2.5V to 5.5V Input Voltage Range}
■ _{1.5MHz Constant Frequency Operation}
■ _{No Schottky Diode Required}
■ _{Low Dropout Operation: 100% Duty Cycle}
■ _{Stable with Ceramic Capacitors}
■ _{Shutdown Mode Draws < 1µA Supply Current}
■ _{±3% Output Voltage Accuracy}
■ _{Current Mode Operation for Excellent Line and}
Load Transient Response
■ _{Overtemperature Protected}
■ _{Low Profile (1mm) ThinSOT}^TM _Package
U
APPLICATIO S
■ _{Cellular Telephones}
■ _{Personal Information Appliances}
■ _{Wireless and DSL Modems}
■ _{Digital Still Cameras}
■ _{MP3 Players}
■ _{Portable Instruments}
DESCRIPTIO
The LTC^®3405A-1.375 is a high efficiency monolithic
synchronous buck regulator using a constant frequency,
current mode architecture. Supply current during opera-
tion is only 20µA and drops to <1µA in shutdown. The 2.5V
to 5.5V input voltage range makes the LTC3405A-1.375
ideally suited for single Li-Ion battery-powered applica-
tions. 100% duty cycle provides low dropout operation,
extending battery life in portable systems.
Switching frequency is internally set at 1.5MHz, allowing
the use of small surface mount inductors and capacitors.
The LTC3405A-1.375 is specifically designed to work well
with ceramic output capacitors, achieving very low output
voltage ripple and a small PCB footprint.
The internal synchronous switch increases efficiency and
eliminates the need for an external Schottky diode. The
LTC3405A-1.375 is available in a low profile (1mm)
ThinSOT package.
For other output voltages, refer to the LTC3405A and
LTC3405A-1.5/LTC3405A-1.8 data sheets.
, 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. All other trademarks are the property of their respective
owners. Protected by U.S. Patents, including 5481178, 6580258, 6304066, 6127815,
6498466, 6611131.
TYPICAL APPLICATIO
V_IN
2.7V
TO 5.5V
C_IN
4.7µF
CER
V_IN
SW
LTC3405A-1.375
4.7µH
RUN
MODE V_OUT
GND
3405A1375 F01
C_OUT
4.7µF
CER
V_OUT
1.375V
300mA
Figure 1a. High Efficiency Step-Down Converter
100
90
80
70
60
50
40
30
0.1
V_IN = 2.7V
V_IN = 3.6V
V_IN = 4.2V
V_IN = 5.5V
1
10
100
OUTPUT CURRENT (mA)
1000
3405A1375 F01b
Figure 1b. Efficiency vs Load Current
3405a1375f
1