LTC3406B
1.5MHz, 600mA
Synchronous Step-Down
Regulator in ThinSOT
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
DESCRIPTIO
High Efficiency: Up to 96%
600mA Output Current at V
IN
= 3V
2.5V to 5.5V Input Voltage Range
1.5MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
Low Quiescent Current: 300µA
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) ThinSOT
TM
Package
The LTC
®
3406B is a high efficiency monolithic synchro-
nous buck regulator using a constant frequency, current
mode architecture. The device is available in an adjustable
version and fixed output voltages of 1.5V and 1.8V. Supply
current with no load is 300µA and drops to <1µA in
shutdown. The 2.5V to 5.5V input voltage range makes the
LTC3406B ideally suited for single Li-Ion battery-powered
applications. 100% duty cycle provides low dropout op-
eration, extending battery life in portable systems. PWM
pulse skipping mode operation provides very low output
ripple voltage for noise sensitive applications.
Switching frequency is internally set at 1.5MHz, allowing
the use of small 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 feed-
back reference voltage. The LTC3406B is available in a low
profile (1mm) ThinSOT package. Refer to LTC3406 for
applications 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.
APPLICATIO S
■
■
■
■
■
■
Cellular Telephones
Personal Information Appliances
Wireless and DSL Modems
Digital Still Cameras
MP3 Players
Portable Instruments
TYPICAL APPLICATIO
100
90
80
4
C
IN
**
4.7µF
CER
1
V
IN
SW
3
VOUT = 1.8V
EFFICIENCY (%)
V
IN
2.7V
TO 5.5V
2.2µH*
C
OUT
†
10µF
CER
V
OUT
1.8V
600mA
70
60
50
40
30
20
10
0.1
VIN = 3.6V
VIN = 2.7V
LTC3406B-1.8
RUN
2
V
OUT
GND
5
3406B F01a
VIN = 4.2V
*MURATA LQH32CN2R2M33
**TAIYO YUDEN JMK212BJ475MG
†
TAIYO YUDEN JMK316BJ106ML
Figure 1a. High Efficiency Step-Down Converter
Figure 1b. Efficiency vs Load Current
3406bfa
U
1
100
10
OUTPUT CURRENT (mA)
1000
3406B F01b
U
U
1