LTC3406B
1.5MHz, 600mA
Synchronous Step-Down
Regulator in ThinSOT
FEATURES
DESCRIPTIO
High Efficiency: Up to 96% The LTC 3406B is a high efficiency monolithic synchro-
600mA Output Current at V = 3V nous buck regulator using a constant frequency, current
IN
2.5V to 5.5V Input Voltage Range mode architecture. The device is available in an adjustable
1.5MHz Constant Frequency Operation version and fixed output voltages of 1.5V and 1.8V. Supply
No Schottky Diode Required
current with no load is 300A and drops to <1A in
Low Dropout Operation: 100% Duty Cycle
shutdown. The 2.5V to 5.5V input voltage range makes the
Low Quiescent Current: 300A
LTC3406B ideally suited for single Li-Ion battery-powered
0.6V Reference Allows Low Output Voltages
applications. 100% duty cycle provides low dropout op-
Shutdown Mode Draws < 1A Supply Current
eration, extending battery life in portable systems. PWM
Current Mode Operation for Excellent Line and
pulse skipping mode operation provides very low output
Load Transient Response
ripple voltage for noise sensitive applications.
Overtemperature Protected
TM Switching frequency is internally set at 1.5MHz, allowing
Low Profile (1mm) ThinSOT Package
the use of small surface mount inductors and capacitors.
U
The internal synchronous switch increases efficiency and
APPLICATIO S
eliminates the need for an external Schottky diode. Low
Cellular Telephones
output voltages are easily supported with the 0.6V feed-
Personal Information Appliances
back reference voltage. The LTC3406B is available in a low
Wireless and DSL Modems
profile (1mm) ThinSOT package. Refer to LTC3406 for
Digital Still Cameras
applications that require Burst Mode operation.
MP3 Players
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
Portable Instruments
ThinSOT is a trademark of Linear Technology Corporation.
Protected by U.S. Patents, including 6580258, 5481178.
TYPICAL APPLICATIO
100
V = 1.8V
OUT
90
80
2.2H*
70
V V
IN
OUT
4 3
V = 3.6V
IN
2.7V V SW 1.8V
IN
60
C
TO 5.5V C ** OUT 600mA
IN
V = 2.7V
10F
4.7F IN
LTC3406B-1.8 50
CER
CER
1 5
3406B F01a 40
RUN V
OUT
GND 30
2 V = 4.2V
IN
20
10
*MURATA LQH32CN2R2M33
0.1 1000
1 10 100
**TAIYO YUDEN JMK212BJ475MG
OUTPUT CURRENT (mA)
TAIYO YUDEN JMK316BJ106ML
3406B F01b
Figure 1a. High Efficiency Step-Down Converter Figure 1b. Efficiency vs Load Current
3406bfa
1
EFFICIENCY (%)
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ULTC3406B
ABSOLUTE AXI U RATI GS (Note 1)
Peak SW Sink and Source Current ........................ 1.3A
Input Supply Voltage .................................. 0.3V to 6V
Operating Temperature Range (Note 2) .. 40C to 85C
RUN, V Voltages ..................................... 0.3V to V
FB IN
Junction Temperature (Notes 3, 6) ...................... 125C
SW Voltage .................................. 0.3V to (V + 0.3V)
IN
Storage Temperature Range ................ 65C to 150C
P-Channel Switch Source Current (DC) ............. 800mA
Lead Temperature (Soldering, 10 sec)................. 300C
N-Channel Switch Sink Current (DC) ................. 800mA
UUW
PACKAGE/ORDER I FOR ATIO
ORDER PART ORDER PART
TOP VIEW TOP VIEW
NUMBER NUMBER
RUN 1 5 V RUN 1 5 V
FB OUT
LTC3406BES5-1.5
LTC3406BES5
GND 2 GND 2
LTC3406BES5-1.8
SW 3 4 V SW 3 4 V
IN IN
S5 PART MARKING S5 PART MARKING
S5 PACKAGE S5 PACKAGE
5-LEAD PLASTIC TSOT-23 5-LEAD PLASTIC TSOT-23
T = 125C, = 250C/ W, = 90C/ W T = 125C, = 250C/ W, = 90C/ W
LTE2 LTE3
JMAX JA JC JMAX JA JC
LTE4
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the full operating
temperature range, otherwise specifications are T = 25C. V = 3.6V unless otherwise specified.
A IN
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I Feedback Current 30 nA
VFB
V Regulated Feedback Voltage LTC3406B (Note 4) T = 25C 0.5880 0.6 0.6120 V
FB A
LTC3406B (Note 4) 0C T 85C 0.5865 0.6 0.6135 V
A
LTC3406B (Note 4) 40C T 85C 0.5850 0.6 0.6150 V
A
V Reference Voltage Line Regulation V = 2.5V to 5.5V (Note 4) 0.04 0.4 %/V
FB IN
V Regulated Output Voltage LTC3406B-1.5 1.455 1.500 1.545 V
OUT
LTC3406B-1.8 1.746 1.800 1.854 V
V Output Overvoltage Lockout V = V V , LTC3406B 20 50 80 mV
OVL OVL OVL FB
V = V V , LTC3406B-1.5/LTC3406B-1.8 2.5 7.8 13 %
OVL OVL OUT
V Output Voltage Line Regulation V = 2.5V to 5.5V 0.04 0.4 %
OUT IN
I Peak Inductor Current V = 3V, V = 0.5V or V = 90%, 0.75 1 1.25 A
PK IN FB OUT
Duty Cycle < 35%
V Output Voltage Load Regulation 0.5 %/V
LOADREG
V Input Voltage Range 2.5 5.5 V
IN
I Input DC Bias Current (Note 5)
S
V = 0.5V or V = 90% 300 400 A
FB OUT
Shutdown V = 0V, V = 4.2V 0.1 1 A
RUN IN
f Oscillator Frequency V = 0.6V or V = 100% 1.2 1.5 1.8 MHz
OSC FB OUT
V = 0V or V = 0V 210 kHz
FB OUT
R R of P-Channel FET I = 100mA 0.4 0.5
PFET DS(ON) SW
R R of N-Channel FET I = 100mA 0.35 0.45
NFET DS(ON) SW
I SW Leakage V = 0V, V = 0V or 5V, V = 5V 0.01 1 A
LSW RUN SW IN
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