LTC3405A-1.8_15 Datasheet, PDF (1/16 Pages) Linear Technology – 1.5V, 1.8V, 1.5MHz, 300mA Synchronous Step-Down Regulators in ThinSOT

LTC3405A-1.5/LTC3405A-1.8
1.5V, 1.8V, 1.5MHz, 300mA
Synchronous Step-Down
Regulators in ThinSOT
FEATURES
■ _{High Efficiency: Up to 93%}
■ _{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}
TYPICAL APPLICATIO
V_IN
2.7V
TO 5.5V
C_IN**
4.7µF
CER
4
V_IN
3 ^4.7µH*
SW
LTC3405A-1.8
1
RUN
6
5
MODE V_OUT
GND
2
3405A1518 F01
*MURATA LQH3C4R7M34
**TAIYO YUDEN JMK212BJ475MG
V_OUT
1.8V
300mA
C_OUT**
4.7µF
CER
Figure 1a. High Efficiency Step-Down Converter
DESCRIPTIO
The LTC^®3405A-1.5/LTC3405A-1.8 are high efficiency
monolithic synchronous buck regulators using a constant
frequency, current mode architecture. Supply current
during operation is only 20µA and drops to <1µA in
shutdown. The 2.5V to 5.5V input voltage range makes the
LTC3405A-1.5/LTC3405A-1.8 ideally suited for single
Li-Ion battery-powered applications. 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-1.5/LTC3405A-1.8 are 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-1.5/LTC3405A-1.8 are available in a low profile
(1mm) ThinSOT package.
For adjustable output voltage, refer to the LTC3405A data
sheet.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
Protected by U.S. Patents, including 6580258, 5481178.
100
V_IN = 2.7V
90
80
V_IN = 3.6V
V_IN = 4.2V
70
V_IN = 5.5V
60
50
40
0.1
1
10
100
OUTPUT CURRENT (mA)
1000
3405A1518 F01b
Figure 1b. Efficiency vs Load Current
3405a1518fa
1