www.docs.chipfind.ru
1
LTC3406B
3406bfa
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: 300A
0.6V Reference Allows Low Output Voltages
Shutdown Mode Draws < 1A 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 300A and drops to <1A 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.
Cellular Telephones
Personal Information Appliances
Wireless and DSL Modems
Digital Still Cameras
MP3 Players
Portable Instruments
Figure 1a. High Efficiency Step-Down Converter
1.5MHz, 600mA
Synchronous Step-Down
Regulator in ThinSOT
Figure 1b. Efficiency vs Load Current
, 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.
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
V
IN
C
IN
**
4.7F
CER
V
IN
2.7V
TO 5.5V
*
**
LTC3406B-1.8
RUN
3
2.2H*
3406B F01a
MURATA LQH32CN2R2M33
TAIYO YUDEN JMK212BJ475MG
TAIYO YUDEN JMK316BJ106ML
5
4
1
2
SW
V
OUT
GND
C
OUT
10F
CER
V
OUT
1.8V
600mA
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10
1000
100
90
80
70
60
50
40
30
20
10
3406B F01b
1
100
VIN = 2.7V
VOUT = 1.8V
VIN = 3.6V
VIN = 4.2V
2
LTC3406B
3406bfa
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
VFB
Feedback Current
30
nA
V
FB
Regulated Feedback Voltage
LTC3406B (Note 4) T
A
= 25C
0.5880
0.6
0.6120
V
LTC3406B (Note 4) 0C T
A
85C
0.5865
0.6
0.6135
V
LTC3406B (Note 4) 40C T
A
85C
0.5850
0.6
0.6150
V
V
FB
Reference Voltage Line Regulation
V
IN
= 2.5V to 5.5V (Note 4)
0.04
0.4
%/V
V
OUT
Regulated Output Voltage
LTC3406B-1.5
1.455
1.500
1.545
V
LTC3406B-1.8
1.746
1.800
1.854
V
V
OVL
Output Overvoltage Lockout
V
OVL
= V
OVL
V
FB
, LTC3406B
20
50
80
mV
V
OVL
= V
OVL
V
OUT
, LTC3406B-1.5/LTC3406B-1.8
2.5
7.8
13
%
V
OUT
Output Voltage Line Regulation
V
IN
= 2.5V to 5.5V
0.04
0.4
%
I
PK
Peak Inductor Current
V
IN
= 3V, V
FB
= 0.5V or V
OUT
= 90%,
0.75
1
1.25
A
Duty Cycle < 35%
V
LOADREG
Output Voltage Load Regulation
0.5
%/V
V
IN
Input Voltage Range
2.5
5.5
V
I
S
Input DC Bias Current
(Note 5)
V
FB
= 0.5V or V
OUT
= 90%
300
400
A
Shutdown
V
RUN
= 0V, V
IN
= 4.2V
0.1
1
A
f
OSC
Oscillator Frequency
V
FB
= 0.6V or V
OUT
= 100%
1.2
1.5
1.8
MHz
V
FB
= 0V or V
OUT
= 0V
210
kHz
R
PFET
R
DS(ON)
of P-Channel FET
I
SW
= 100mA
0.4
0.5
R
NFET
R
DS(ON)
of N-Channel FET
I
SW
= 100mA
0.35
0.45
I
LSW
SW Leakage
V
RUN
= 0V, V
SW
= 0V or 5V, V
IN
= 5V
0.01
1
A
LTC3406BES5
T
JMAX
= 125C,
JA
= 250C/ W,
JC
= 90C/ W
ORDER PART
NUMBER
Input Supply Voltage .................................. 0.3V to 6V
RUN, V
FB
Voltages ..................................... 0.3V to V
IN
SW Voltage .................................. 0.3V to (V
IN
+ 0.3V)
P-Channel Switch Source Current (DC) ............. 800mA
N-Channel Switch Sink Current (DC) ................. 800mA
S5 PART MARKING
Consult LTC Marketing for parts specified with wider operating temperature ranges.
LTE2
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
Peak SW Sink and Source Current ........................ 1.3A
Operating Temperature Range (Note 2) .. 40C to 85C
Junction Temperature (Notes 3, 6) ...................... 125C
Storage Temperature Range ................ 65C to 150C
Lead Temperature (Soldering, 10 sec)................. 300C
LTC3406BES5-1.5
LTC3406BES5-1.8
ORDER PART
NUMBER
S5 PART MARKING
LTE3
LTE4
T
JMAX
= 125C,
JA
= 250C/ W,
JC
= 90C/ W
RUN 1
GND 2
SW 3
5 V
OUT
4 V
IN
TOP VIEW
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
The
denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25C. V
IN
= 3.6V unless otherwise specified.
ELECTRICAL CHARACTERISTICS
RUN 1
GND 2
SW 3
5 V
FB
4 V
IN
TOP VIEW
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
3
LTC3406B
3406bfa
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
RUN
RUN Threshold
0.3
1
1.5
V
I
RUN
RUN Leakage Current
0.01
1
A
The
denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25C. V
IN
= 3.6V unless otherwise specified.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3406BE is guaranteed to meet performance specifications
from 0C to 70C. Specifications over the 40C to 85C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LTC3406B: T
J
= T
A
+ (P
D
)(250C/W)
Note 4: The LTC3406B is tested in a proprietary test mode that connects
V
FB
to the output of the error amplifier.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Efficiency vs Input Voltage
Efficiency vs Output Current
Efficiency vs Output Current
Efficiency vs Output Current
Reference Voltage vs
Temperature
Oscillator Frequency vs
Temperature
(From Figure1a Except for the Resistive Divider Resistor Values)
TEMPERATURE (C)
50
REFERENCE VOLTAGE (V)
0.614
0.609
0.604
0.599
0.594
0.589
0.584
25
75
25
0
50
100
125
V
IN
= 3.6V
3406B G05
TEMPERATURE (C)
50
FREQUENCY (MHz)
1.70
1.65
1.60
1.55
1.50
1.45
1.40
1.35
1.30
25
75
25
0
50
100
125
V
IN
= 3.6V
3406B G06
INPUT VOLTAGE (V)
2
EFFICIENCY (%)
6
3406B G01
3
4
5
100
95
90
85
80
75
70
65
60
55
50
I
OUT
= 600mA
I
OUT
= 100mA
I
OUT
= 10mA
T
A
= 25C
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10
1000
100
90
80
70
60
50
40
30
20
10
3406B GO2
1
100
V
OUT
= 1.2V
T
A
= 25C
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10
1000
100
90
80
70
60
50
40
30
20
10
3406B GO3
1
100
V
OUT
= 1.5V
T
A
= 25C
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10
1000
100
90
80
70
60
50
40
30
20
10
3406B G04
1
100
V
OUT
= 2.5V
T
A
= 25C
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
4
LTC3406B
3406bfa
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Oscillator Frequency vs
Supply Voltage
Output Voltage vs Load Current
R
DS(ON
) vs Input Voltage
(From Figure1a Except for the Resistive Divider Resistor Values)
SUPPLY VOLTAGE (V)
2
OSCILLATOR FREQUENCY (MHz)
1.8
1.7
1.6
1.5
1.4
1.3
1.2
3
4
5
6
3406B G07
T
A
= 25C
INPUT VOLTAGE (V)
1
0
0.4
0.5
0.7
4
6
3406B G09
0.3
0.2
2
3
5
7
0.1
0
0.6
R
DS(ON)
(
)
MAIN
SWITCH
SYNCHRONOUS
SWITCH
T
A
= 25C
R
DS(ON)
vs Temperature
Dynamic Supply Current vs
Supply Voltage
Dynamic Supply Current vs
Temperature
Switch Leakage vs Temperature
Switch Leakage vs Input Voltage
Discontinuous Operation
TEMPERATURE (C)
50
0.4
0.5
0.7
25
75
3406B G10
0.3
0.2
25
0
50
100
125
0.1
0
0.6
R
DS(ON)
(
)
MAIN SWITCH
SYNCHRONOUS SWITCH
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
TEMPERATURE (C)
50
SWITCH LEAKAGE (nA)
200
250
300
25
75
3406B G13
150
100
25
0
50
100
125
50
0
V
IN
= 5.5V
RUN = 0V
MAIN SWITCH
SYNCHRONOUS SWITCH
INPUT VOLTAGE (V)
0
0
SWITCH LEAKAGE (pA)
20
40
60
80
120
1
2
3
4
3406B G14
5
6
100
RUN = 0V
T
A
= 25C
SYNCHRONOUS
SWITCH
MAIN
SWITCH
LOAD CURRENT (mA)
0
OUTPUT VOLTAGE (V)
500
200 300 400
600
800
100
1.844
1.834
1.824
1.814
1.804
1.794
1.784
1.774
3406B G08
900
700
V
IN
= 3.6V
T
A
= 25C
SUPPLY VOLTAGE (V)
2
DYNAMIC SUPPLY CURRENT (
A)
6
3406B G11
3
4
5
400
380
360
340
320
300
280
260
240
220
200
V
OUT
= 1.8V
I
LOAD
= 0A
T
A
= 25C
TEMPERATURE (C)
50
340
320
300
280
260
240
220
200
25
75
3406B G12
25
0
50
100
125
DYNAMIC SUPPLY CURRENT (
A)
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 0A
SW
2V/DIV
V
OUT
10mV/DIV
AC COUPLED
I
L
200mA/DIV
1s/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 50mA
3406B G15
5
LTC3406B
3406bfa
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
(From Figure 1a Except for the Resistive Divider Resistor Values)
Start-Up from Shutdown
Load Step
Load Step
Load Step
Load Step
U
U
U
PI FU CTIO S
RUN (Pin 1): Run Control Input. Forcing this pin above
1.5V enables the part. Forcing this pin below 0.3V shuts
down the device. In shutdown, all functions are disabled
drawing <1A supply current. Do not leave RUN floating.
GND (Pin 2): Ground Pin.
SW (Pin 3): Switch Node Connection to Inductor. This pin
connects to the drains of the internal main and synchro-
nous power MOSFET switches.
V
IN
(Pin 4): Main Supply Pin. Must be closely decoupled
to GND, Pin 2, with a 2.2F or greater ceramic capacitor.
V
FB
(Pin 5) (LTC3406B): Feedback Pin. Receives the
feedback voltage from an external resistive divider across
the output.
V
OUT
(Pin 5) (LTC3406B-1.5/LTC3406B-1.8): Output Volt-
age Feedback Pin. An internal resistive divider divides the
output voltage down for comparison to the internal refer-
ence voltage.
RUN
5V/DIV
V
OUT
1V/DIV
I
L
500mA/DIV
40s/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 600mA (LOAD: 3 RESISTOR)
3406B G16
V
OUT
100mV/DIV
AC COUPLED
I
L
500mA/DIV
I
LOAD
500mA/DIV
20s/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 0mA TO 600mA
3406B G17
V
OUT
100mV/DIV
AC COUPLED
I
LOAD
500mA/DIV
I
L
500mA/DIV
20s/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 50mA TO 600mA
3406B G18
V
OUT
100mV/DIV
AC COUPLED
I
L
500mA/DIV
I
LOAD
500mA/DIV
20s/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 100mA TO 600mA
3406B G19
V
OUT
100mV/DIV
AC COUPLED
I
L
500mA/DIV
I
LOAD
500mA/DIV
20s/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 200mA TO 600mA
3406B G20
PDF 
ZIP