LTC3406
LTC3406-1.5/LTC3406-1.8
1.5MHz, 600mA
Synchronous Step-Down
Regulator in ThinSOT
FEATURES
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DESCRIPTIO
High Efficiency: Up to 96%
Very Low Quiescent Current: Only 20
µ
A
During Operation
600mA Output Current
2.5V to 5.5V Input Voltage Range
1.5MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
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
®
3406 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 during operation is only 20µA and drops to
≤1µA
in shutdown. The 2.5V to 5.5V input voltage range makes
the LTC3406 ideally suited for single Li-Ion battery-pow-
ered applications. 100% duty cycle provides low dropout
operation, extending battery life in portable systems.
Automatic Burst Mode
®
operation increases efficiency at
light loads, further extending battery life.
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 LTC3406 is available in a low
profile (1mm) ThinSOT package.
, 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
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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
4
C
IN
**
4.7µF
CER
1
3
95
90
2.2µH*
C
OUT
†
10µF
CER
5
3406 F01a
V
IN
= 2.7V
EFFICIENCY (%)
V
IN
SW
V
OUT
1.8V
600mA
85
V
IN
= 3.6V
80
V
IN
= 4.2V
75
70
65
60
0.1
V
OUT
= 1.8V
1
10
100
OUTPUT CURRENT (mA)
1000
3406 F01b
LTC3406-1.8
RUN
V
OUT
2
GND
*MURATA LQH32CN2R2M33
**TAIYO YUDEN JMK212BJ475MG
†
TAIYO YUDEN JMK316BJ106ML
Figure 1a. High Efficiency Step-Down Converter
Figure 1b. Efficiency vs Load Current
3406fa
U
U
U
1