LTC3406B Datasheet by Analog Devices Inc.

View All Related Products | Download PDF Datasheet
LTCBAOéB _| ECHNOLOGY L7 mo 90 an a? 70 VW sw g 60 2 mama“ g 59 mm err mm. m 40 GND so 20 . m MURATA LflHSZCNZRZMSS "1AM: VUDEM JMKzrzamsMs 0‘ ‘ ‘0 ‘00 ‘0 mm: mm: JMKSISEJIDSML ouwm CURRENT (mAj Figure 13. High Eiiiciency Slep-Down Convener Figure 1b. Eiiiciency vs Lnad Curren L7LJCUW
1
LTC34 0 6B
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: 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.
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
**
4.7µF
CER
V
IN
2.7V
TO 5.5V
*
**
LTC3406B-1.8
RUN
32.2µH*
3406B F01a
MURATA LQH32CN2R2M33
TAIYO YUDEN JMK212BJ475MG
TAIYO YUDEN JMK316BJ106ML
5
4
1
2
SW
V
OUT
GND
C
OUT
10µF
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
WU U U WU U U L7LJUEAR
2
LTC34 0 6B
3406bfa
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
VFB
Feedback Current ±30 nA
V
FB
Regulated Feedback Voltage LTC3406B (Note 4) T
A
= 25°C 0.5880 0.6 0.6120 V
LTC3406B (Note 4) 0°C T
A
85°C 0.5865 0.6 0.6135 V
LTC3406B (Note 4) –40°C T
A
85°C0.5850 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 µA
Shutdown V
RUN
= 0V, V
IN
= 4.2V 0.1 1 µA
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 ±1µA
LTC3406BES5
T
JMAX
= 125°C, θ
JA
= 250°C/ W, θ
JC
= 90°C/ 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
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
(Note 1)
Peak SW Sink and Source Current ........................ 1.3A
Operating Temperature Range (Note 2) .. 40°C to 85°C
Junction Temperature (Notes 3, 6) ...................... 125°C
Storage Temperature Range ................ 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
LTC3406BES5-1.5
LTC3406BES5-1.8
ORDER PART
NUMBER
S5 PART MARKING
LTE3
LTE4
T
JMAX
= 125°C, θ
JA
= 250°C/ W, θ
JC
= 90°C/ 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 TA = 25°C. VIN = 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
mu “45°C mu me 95 \uwmnm 9“ an so an an 35 \uwsnnm 3 70 V 80 i; 5 ) E 75 InwwmA % 60 E 50 E 70 g 50 E 5a m 65 w 40 u. 4g 60 30 ED 55 20 ED 50 H] W 2 3 4 5 5 or I m me man or V n: mu m ‘NPUT VOLTAGE (V) 0mm CURRENT (mA) ouwu'r CURRENT (mA) Relerence anlage vs Oscillator Frequency vs Iency vs Output Current Temperature Temperature IUD 06M \ V70 vw=zsv VW=35V an Vw= N 0609 ‘55 5" : ran 70 gnaw: g ‘55 5 5" S f ; 5 50599 S 150 a so u g E E E Ms W 40 $0594 5 30 I ‘40 20 vm=3 "539 was ID 0584 ‘30 m w m mu m 750 725 n 25 so 75 um ‘25 75D 725 u 25 so 75 um 12 ouwurcuanmnm) rEMPEnAmREm TEMPERATURE(“C) Must: L7LJCUW 3
3
LTC34 0 6B
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 ±1µA
The denotes specifications which apply over the full operating
temperature range, otherwise specifications are TA = 25°C. VIN = 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 0°C to 70°C. Specifications over the –40°C to 85°C 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
)(250°C/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 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
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
345
100
95
90
85
80
75
70
65
60
55
50
I
OUT
= 600mA
I
OUT
= 100mA
I
OUT
= 10mA
T
A
= 25°C
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
= 25°CVIN = 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
= 25°CVIN = 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
= 25°C
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
T3 T7 T5 T5 H a g § § E K 9 E a T3 T2 07 as 05 on na 02 m a MATN sWTTcH \0\\ 2 3 4 5 E SUPPLV VOLTAGE (V) Rnswm vs Temparature — MAW sWTTCH - SVNCHRONOUS SWITCH 750 725 u 25 50 75 Too I25 TEMPERATURE Us) Switch Leakage vs Temperalure T m 200 2 a 4 5 E SUPPLV VOLTAGE (V) Switch Leakage vs Inpul Voltage a I 2 3 a 5 5 7 INPUT VOLTAGE (V) 200 750 725 a 25 50 75 Too T2 TEMPERATURE we) Discuntinunus Dparaliun 300 T20 n ‘ . g3; / “mm/f TLVLVLTVLVTLTTLVT I w W/ ; um mm ‘L‘\ “\Q E 50 MATNSWTTCH/ m 20 ' ' 5 a SVNCHRONOUS SWW // 750 725 u 25 50 75 Too I25 TEMPERATUREUC) u T 2 3 4 5 E WPUT VOLTAGE (V) Mush
4
LTC34 0 6B
3406bfa
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Oscillator Frequency vs
Supply Voltage Output Voltage vs Load Current RDS(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 34 56
3406B G07
TA = 25°C
INPUT VOLTAGE (V)
10
0.4
0.5
0.7
46
3406B G09
0.3
0.2
23 57
0.1
0
0.6
R
DS(ON)
()
MAIN
SWITCH
SYNCHRONOUS
SWITCH
T
A
= 25°C
RDS(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
1234
3406B G14
56
100
RUN = 0V
TA = 25°C
SYNCHRONOUS
SWITCH
MAIN
SWITCH
LOAD CURRENT (mA)
0
OUTPUT VOLTAGE (V)
500200 300 400 600 800100
1.844
1.834
1.824
1.814
1.804
1.794
1.784
1.774
3406B G08
900700
V
IN
= 3.6V
T
A
= 25°C
SUPPLY VOLTAGE (V)
2
DYNAMIC SUPPLY CURRENT (µA)
6
3406B G11
345
400
380
360
340
320
300
280
260
240
220
200
V
OUT
= 1.8V
I
LOAD
= 0A
T
A
= 25°C
TEMPERATURE (°C)
–50
340
320
300
280
260
240
220
200
25 75
3406B G12
–25 0 50 100 125
DYNAMIC SUPPLY CURRENT (µA)
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 0A
SW
2V/DIV
V
OUT
10mV/DIV
AC COUPLED
I
L
200mA/DIV
1µs/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 50mA
3406B G15
L7LJCUW%
5
LTC34 0 6B
3406bfa
TYPICAL PERFOR A CE CHARACTERISTICS
UW
(From Figure 1a Except for the Resistive Divider Resistor Values)
Start-Up from Shutdown Load Step Load Step
Load Step Load Step
UU
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 <1µA 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 2.2µF 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
40µs/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 600mA (LOAD: 3 RESISTOR)
3406B G16
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.8V
ILOAD = 0mA TO 600mA
3406B G17
VOUT
100mV/DIV
AC COUPLED
ILOAD
500mA/DIV
IL
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.8V
ILOAD = 50mA TO 600mA
3406B G18
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.8V
ILOAD = 100mA TO 600mA
3406B G19
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.8V
ILOAD = 200mA TO 600mA
3406B G20
TCSADEBVT a w + R2 = 540k FREQ SHTFT RUN E‘— UEVREF H mm avm | _|_ T T —r TIT I SHUTDOWN ITT ‘ncw El 340 L7LJHEAR
6
LTC34 0 6B
3406bfa
FU CTIO AL DIAGRA
UU
W
+
+
EA
+
IRCMP
+
ICOMP
5
1
RUN
OSC
SLOPE
COMP
OSC
FREQ
SHIFT
0.6V
FB
0.6V + VOVL
R1LTC3406B-1.5
R1 + R2 = 550k
LTC3406B-1.8
R1 + R2 = 540k R2
0.6V REF
SHUTDOWN
VIN
VFB/VOUT
VIN
S
R
RS LATCH
OV
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
ANTI-
SHOOT-
THRU
Q
Q
5
4
SW
3
GND
3406B BD
2
+
OVDET
OPERATIO
U
(Refer to Functional Diagram)
Main Control Loop
The LTC3406B uses a constant frequency, current mode
step-down architecture. Both the main (P-channel
MOSFET) and synchronous (N-channel MOSFET) switches
are internal. During normal operation, the internal top
power MOSFET is turned on each cycle when the oscillator
sets the RS latch, and turned off when the current com-
parator, I
COMP
, resets the RS latch. The peak inductor
current at which I
COMP
resets the RS latch, is controlled by
the output of error amplifier EA. When the load current
increases, it causes a slight decrease in the feedback
voltage, FB, relative to the 0.6V reference, which in turn,
causes the EA amplifier’s output voltage to increase until
the average inductor current matches the new load cur-
rent. While the top MOSFET is off, the bottom MOSFET is
turned on until either the inductor current starts to reverse,
as indicated by the current reversal comparator I
RCMP
, or
the beginning of the next clock cycle. The comparator
OVDET guards against transient overshoots >7.8% by
turning the main switch off and keeping it off until the fault
is removed.
Pulse Skipping Mode Operation
At light loads, the inductor current may reach zero or re-
verse on each pulse. The bottom MOSFET is turned off by
the current reversal comparator, I
RCMP
, and the switch
voltage will ring. This is discontinuous mode operation,
and is normal behavior for the switching regulator. At very
light loads, the LTC3406B will automatically skip pulses in
pulse skipping mode operation to maintain output regula-
tion. Refer to LTC3406 data sheet if Burst Mode operation
is preferred.
Short-Circuit Protection
When the output is shorted to ground, the frequency of the
oscillator is reduced to about 210kHz, 1/7 the nominal
frequency. This frequency foldback ensures that the in-
ductor current has more time to decay, thereby preventing
runaway. The oscillator’s frequency will progressively
increase to 1.5MHz when V
FB
or V
OUT
rises above 0V.
\\ vum: I av \\ vw = 2 5v L7LJCUW
7
LTC34 0 6B
3406bfa
OPERATIO
U
(Refer to Functional Diagram)
Dropout Operation
As the input supply voltage decreases to a value approach-
ing the output voltage, the duty cycle increases toward the
maximum on-time. Further reduction of the supply voltage
forces the main switch to remain on for more than one cycle
until it reaches 100% duty cycle. The output voltage will then
be determined by the input voltage minus the voltage drop
across the P-channel MOSFET and the inductor.
An important detail to remember is that at low input supply
voltages, the R
DS(ON)
of the P-channel switch increases
(see Typical Performance Characteristics). Therefore, the
user should calculate the power dissipation when the
LTC3406B is used at 100% duty cycle with low input
voltage (See Thermal Considerations in the Applications
Information section).
Low Supply Operation
The LTC3406B will operate with input supply voltages as
low as 2.5V, but the maximum allowable output current is
reduced at this low voltage. Figure 2 shows the reduction
in the maximum output current as a function of input
voltage for various output voltages.
Slope Compensation and Inductor Peak Current
Slope compensation provides stability in constant fre-
quency architectures by preventing subharmonic oscilla-
tions at high duty cycles. It is accomplished internally by
adding a compensating ramp to the inductor current
signal at duty cycles in excess of 40%. Normally, this
results in a reduction of maximum inductor peak current
for duty cycles >40%. However, the LTC3406B uses a
patent-pending scheme that counteracts this compensat-
ing ramp, which allows the maximum inductor peak
current to remain unaffected throughout all duty cycles.
SUPPLY VOLTAGE (V)
2.5
MAXIMUM OUTPUT CURRENT (mA)
1200
1000
800
600
400
200
03.0 3.5 4.0 4.5
3406B F02
5.0 5.5
V
OUT
= 1.8V
V
OUT
= 1.5V
V
OUT
= 2.5V
Figure 2. Maximum Output Current vs Input Voltage
L7LJUEAR
8
LTC34 0 6B
3406bfa
APPLICATIO S I FOR ATIO
WUUU
The basic LTC3406B application circuit is shown in Figure
1. External component selection is driven by the load
requirement and begins with the selection of L followed by
C
IN
and C
OUT
.
Inductor Selection
For most applications, the value of the inductor will fall in
the range of 1µH to 4.7µH. Its value is chosen based on the
desired ripple current. Large value inductors lower ripple
current and small value inductors result in higher ripple
currents. Higher V
IN
or V
OUT
also increases the ripple
current as shown in equation 1. A reasonable starting point
for setting ripple current is I
L
= 240mA (40% of 600mA).
=
()( )
IfL
VV
V
L OUT OUT
IN
11
(1)
The DC current rating of the inductor should be at least
equal to the maximum load current plus half the ripple
current to prevent core saturation. Thus, a 720mA rated
inductor should be enough for most applications (600mA
+ 120mA). For better efficiency, choose a low DC-resis-
tance inductor.
Inductor Core Selection
Different core materials and shapes will change the size/
current and price/current relationship of an inductor.
Toroid or shielded pot cores in ferrite or permalloy mate-
rials are small and don’t radiate much energy, but gener-
ally cost more than powdered iron core inductors with
similar electrical characteristics. The choice of which style
inductor to use often depends more on the price vs size
requirements and any radiated field/EMI requirements
than on what the LTC3406B requires to operate. Table 1
shows some typical surface mount inductors that work
well in LTC3406B applications.
Table 1. Representative Surface Mount Inductors
PART VALUE DCR MAX DC SIZE
NUMBER (µH) ( MAX) CURRENT (A) W × L × H (mm
3
)
Sumida 1.5 0.043 1.55 3.8 × 3.8 × 1.8
CDRH3D16 2.2 0.075 1.20
3.3 0.110 1.10
4.7 0.162 0.90
Sumida 2.2 0.116 0.950 3.5 × 4.3 × 0.8
CMD4D06 3.3 0.174 0.770
4.7 0.216 0.750
Panasonic 3.3 0.17 1.00 4.5 × 5.4 × 1.2
ELT5KT 4.7 0.20 0.95
Murata 1.0 0.060 1.00 2.5 × 3.2 × 2.0
LQH3C 2.2 0.097 0.79
4.7 0.150 0.65
C
IN
and C
OUT
Selection
In continuous mode, the source current of the top MOSFET
is a square wave of duty cycle V
OUT
/V
IN
. To prevent large
voltage transients, a low ESR input capacitor sized for the
maximum RMS current must be used. The maximum
RMS capacitor current is given by:
CI
VVV
V
IN OMAX
OUT IN OUT
IN
required IRMS
()
[]
12/
This formula has a maximum at V
IN
= 2V
OUT
, where
I
RMS
= I
OUT
/2. This simple worst-case condition is com-
monly used for design because even significant deviations
do not offer much relief. Note that the capacitor
manufacturer’s ripple current ratings are often based on
2000 hours of life. This makes it advisable to further derate
the capacitor, or choose a capacitor rated at a higher
temperature than required. Always consult the manufac-
turer if there is any question.
The selection of C
OUT
is driven by the required effective
series resistance (ESR).
L7LJCUW
9
LTC34 0 6B
3406bfa
Typically, once the ESR requirement for C
OUT
has been
met, the RMS current rating generally far exceeds the
I
RIPPLE(P-P)
requirement. The output ripple V
OUT
is deter-
mined by:
∆≅+
V I ESR fC
OUT L
OUT
1
8
where f = operating frequency, C
OUT
= output capacitance
and I
L
= ripple current in the inductor. For a fixed output
voltage, the output ripple is highest at maximum input
voltage since I
L
increases with input voltage.
Aluminum electrolytic and dry tantalum capacitors are
both available in surface mount configurations. In the case
of tantalum, it is critical that the capacitors are surge tested
for use in switching power supplies. An excellent choice is
the AVX TPS series of surface mount tantalum. These are
specially constructed and tested for low ESR so they give
the lowest ESR for a given volume. Other capacitor types
include Sanyo POSCAP, Kemet T510 and T495 series, and
Sprague 593D and 595D series. Consult the manufacturer
for other specific recommendations.
Using Ceramic Input and Output Capacitors
Higher values, lower cost ceramic capacitors are now
becoming available in smaller case sizes. Their high ripple
current, high voltage rating and low ESR make them ideal
for switching regulator applications. Because the
LTC3406B’s control loop does not depend on the output
capacitor’s ESR for stable operation, ceramic capacitors
can be used freely to achieve very low output ripple and
small circuit size.
However, care must be taken when ceramic capacitors are
used at the input and the output. When a ceramic capacitor
is used at the input and the power is supplied by a wall
adapter through long wires, a load step at the output can
induce ringing at the input, V
IN
. At best, this ringing can
APPLICATIO S I FOR ATIO
WUUU
couple to the output and be mistaken as loop instability. At
worst, a sudden inrush of current through the long wires
can potentially cause a voltage spike at V
IN
, large enough
to damage the part.
When choosing the input and output ceramic capacitors,
choose the X5R or X7R dielectric formulations. These
dielectrics have the best temperature and voltage charac-
teristics of all the ceramics for a given value and size.
Output Voltage Programming (LTC3406B Only)
In the adjustable version, the output voltage is set by a
resistive divider according to the following formula:
VV
R
R
OUT
=+
06 1 2
1
.
(2)
The external resistive divider is connected to the output,
allowing remote voltage sensing as shown in Figure 3.
Figure 3. Setting the LTC3406B Output Voltage
V
FB
GND
LTC3406B
0.6V V
OUT
5.5V
R2
R1
3406B F03
Efficiency Considerations
The efficiency of a switching regulator is equal to the
output power divided by the input power times 100%. It is
often useful to analyze individual losses to determine what
is limiting the efficiency and which change would produce
the most improvement. Efficiency can be expressed as:
Efficiency = 100% – (L1 + L2 + L3 + ...)
where L1, L2, etc. are the individual losses as a percentage
of input power.
o I l in ma mo LDAD comm (mAl Figure 4. Power Lnstvs Load Eurren 1. The ViN quiescent current is due to two c the DC bias current as given in the electric istics and the internal main switch and switch gate charge currents. The gate ch results from swrtching the gate capaci internal powerMOSFET switches. Each tim switched from high to low to high again charge, d0, moves from VIN to ground. dO/dtisthe currentoutofViNthatistypica the DC bias current. In continuous mod f(0T+ 03) where Grand 05 are the gate c internal top and bottom swrtches. Both th gate charge losses are proportional to their effects will be more pronounced at h voltages. 1 O L7LJHEAR
10
LTC34 0 6B
3406bfa
APPLICATIO S I FOR ATIO
WUUU
Although all dissipative elements in the circuit produce
losses, two main sources usually account for most of the
losses in LTC3406B circuits: V
IN
quiescent current and I
2
R
losses. The V
IN
quiescent current loss dominates the
efficiency loss at very low load currents whereas the I
2
R
loss dominates the efficiency loss at medium to high load
currents. In a typical efficiency plot, the efficiency curve at
very low load currents can be misleading since the actual
power lost is of no consequence as illustrated in Figure 4.
2. I
2
R losses are calculated from the resistances of the
internal switches, R
SW
, and external inductor R
L
. In
continuous mode, the average output current flowing
through inductor L is “chopped” between the main
switch and the synchronous switch. Thus, the series
resistance looking into the SW pin is a function of both
top and bottom MOSFET R
DS(ON)
and the duty cycle
(DC) as follows:
R
SW
= (R
DS(ON)TOP
)(DC) + (R
DS(ON)BOT
)(1 – DC)
The R
DS(ON)
for both the top and bottom MOSFETs can
be obtained from the Typical Performance Charateristics
curves. Thus, to obtain I
2
R losses, simply add R
SW
to
R
L
and multiply the result by the square of the average
output current.
Other losses including C
IN
and C
OUT
ESR dissipative
losses and inductor core losses generally account for less
than 2% total additional loss.
Thermal Considerations
In most applications the LTC3406B does not dissipate
much heat due to its high efficiency. But, in applications
where the LTC3406B is running at high ambient tempera-
ture with low supply voltage and high duty cycles, such
as in dropout, the heat dissipated may exceed the maxi-
mum junction temperature of the part. If the junction
temperature reaches approximately 150°C, both power
switches will be turned off and the SW node will become
high impedance.
To avoid the LTC3406B from exceeding the maximum
junction temperature, the user will need to do some
thermal analysis. The goal of the thermal analysis is to
determine whether the power dissipated exceeds the
maximum junction temperature of the part. The tempera-
ture rise is given by:
T
R
= (P
D
)(θ
JA
)
where P
D
is the power dissipated by the regulator and θ
JA
is the thermal resistance from the junction of the die to the
ambient temperature.
Figure 4. Power Lost vs Load Current
1. The V
IN
quiescent current is due to two components:
the DC bias current as given in the electrical character-
istics and the internal main switch and synchronous
switch gate charge currents. The gate charge current
results from switching the gate capacitance of the
internal power MOSFET switches. Each time the gate is
switched from high to low to high again, a packet of
charge, dQ, moves from V
IN
to ground. The resulting
dQ/dt is the current out of V
IN
that is typically larger than
the DC bias current. In continuous mode, I
GATECHG
=
f(Q
T
+ Q
B
) where Q
T
and Q
B
are the gate charges of the
internal top and bottom switches. Both the DC bias and
gate charge losses are proportional to V
IN
and thus
their effects will be more pronounced at higher supply
voltages.
LOAD CURRENT (mA)
POWER LOSS (W)
0.1 10 100 1000
3406B F04
1
1
0.1
0.01
0.001
0.0001
VOUT = 1.2V
VOUT = 1.8V
VOUT = 2.5V
VOUT = 1.5V
VIN = 3.6V
L7LJCUW
11
LTC34 0 6B
3406bfa
APPLICATIO S I FOR ATIO
WUUU
The junction temperature, T
J
, is given by:
T
J
= T
A
+ T
R
where T
A
is the ambient temperature.
As an example, consider the LTC3406B in dropout at an
input voltage of 2.7V, a load current of 600mA and an
ambient temperature of 70°C. From the typical perfor-
mance graph of switch resistance, the R
DS(ON)
of the
P-channel switch at 70°C is approximately 0.52. There-
fore, power dissipated by the part is:
P
D
= I
LOAD2
• R
DS(ON)
= 187.2mW
For the SOT-23 package, the θ
JA
is 250°C/W. Thus, the
junction temperature of the regulator is:
T
J
= 70°C + (0.1872)(250) = 116.8°C
which is below the maximum junction temperature of
125°C.
Note that at higher supply voltages, the junction tempera-
ture is lower due to reduced switch resistance (R
DS(ON)
).
Checking Transient Response
The regulator loop response can be checked by looking at
the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, V
OUT
immediately shifts by an amount
equal to (I
LOAD
• ESR), where ESR is the effective series
resistance of C
OUT
. I
LOAD
also begins to charge or
discharge C
OUT
, which generates a feedback error signal.
The regulator loop then acts to return V
OUT
to its steady-
state value. During this recovery time V
OUT
can be moni-
tored for overshoot or ringing that would indicate a stability
problem. For a detailed explanation of switching control
loop theory, see Application Note 76.
A second, more severe transient is caused by switching in
loads with large (>1µF) supply bypass capacitors. The
discharged bypass capacitors are effectively put in parallel
with C
OUT
, causing a rapid drop in V
OUT
. No regulator can
deliver enough current to prevent this problem if the load
switch resistance is low and it is driven quickly. The only
solution is to limit the rise time of the switch drive so that
the load rise time is limited to approximately (25 • C
LOAD
).
Thus, a 10µF capacitor charging to 3.3V would require a
250µs rise time, limiting the charging current to about
130mA.
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC3406B. These items are also illustrated graphically in
Figures 5 and 6. Check the following in your layout:
1. The power traces, consisting of the GND trace, the SW
trace and the V
IN
trace should be kept short, direct and
wide.
2. Does the V
FB
pin connect directly to the feedback
resistors? The resistive divider R1/R2 must be con-
nected between the (+) plate of C
OUT
and ground.
3. Does the (+) plate of C
IN
connect to V
IN
as closely as
possible? This capacitor provides the AC current to the
internal power MOSFETs.
4. Keep the switching node, SW, away from the sensitive
V
FB
node.
5. Keep the (–) plates of C
IN
and C
OUT
as close as possible.
:1 I" var" r_r |:| mamas LI 5W El - :|Coui[sfin:| Cw [ - Figure 6a. LT034l1lil! Suggested Laynut Design Example As a design example, assume the LTCS4OGB is used in a single lithium-ion battery-powered cellular phone applicationTheVW willbe operatingfromamaximum of 4.2V down to about 2.7V. The load current requirement is a maximum of 0.6A but most of the time it will be in standbymode,reouiring only2mA. Efficienoyatboth low and high load currents is important. Output voltage is 2.5V. With this information we can calculate L using equation (1), 1 ( L= V0 r AIL ”TL Vnuv flflfl LI Substituting Vour : f: 1.5MHz in equa _ 2.5V 1.5MHz(240m A 2.2nH inductorw efficiency choose a than 0.252 series re CIN will require an ILOAD(MAX)/2 at tem of lessthan 0.259. satisfy thrs requrre 12 L7LJHEAR
12
LTC34 0 6B
3406bfa
APPLICATIO S I FOR ATIO
WUUU
Design Example
As a design example, assume the LTC3406B is used in a
single lithium-ion battery-powered cellular phone
application. The V
IN
will be operating from a maximum of
4.2V down to about 2.7V. The load current requirement
is a maximum of 0.6A but most of the time it will be in
standby mode, requiring only 2mA. Efficiency at both low
and high load currents is important. Output voltage is
2.5V. With this information we can calculate L using
equation (1),
LfI
VV
V
L
OUT OUT
IN
=
()
()
11
(3)
Figure 5a. LTC3406B Layout Diagram
Figure 6a. LTC3406B Suggested Layout
Substituting V
OUT
= 2.5V, V
IN
= 4.2V, I
L
= 240mA and
f = 1.5MHz in equation (3) gives:
LV
MHz mA
V
VH=
25
1 5 240 125
42 281
.
.( )
.
..
A 2.2µH inductor works well for this application. For best
efficiency choose a 720mA or greater inductor with less
than 0.2 series resistance.
C
IN
will require an RMS current rating of at least 0.3A
I
LOAD(MAX)
/2 at temperature and C
OUT
will require an ESR
of less than 0.25. In most cases, a ceramic capacitor will
satisfy this requirement.
RUN
LTC3406B
GND
SW
L1
R2 R1
C
FWD
BOLD LINES INDICATE HIGH CURRENT PATHS
V
IN
V
OUT
3406B F05a
4
5
1
3
+
2
V
FB
V
IN
C
IN
+
C
OUT
RUN
LTC3406B-1.8
GND
SW
L1
BOLD LINES INDICATE HIGH CURRENT PATHS
V
IN
V
OUT
3406B F05b
4
5
1
3
+
2V
OUT
V
IN
C
IN
C
OUT
Figure 5b. LTC3406B-1.8 Layout Diagram
LTC3406B
GND
3406B F06a
PIN 1
V
OUT
V
IN
VIA TO V
OUT
SW
VIA TO V
IN
VIA TO GND
C
OUT
C
IN
L1
R2
C
FWD
R1
LTC3406B-1.8
GND
3406B F06b
PIN 1
V
OUT
V
IN
SW
VIA TO V
IN
VIA TO V
OUT
C
OUT
C
IN
L1
Figure 6b. LTC3406B-1.8 Suggested Layout
R2=Wfl—1\R1=1000k L06 J Inn an an m Vw 3/ Vum > 50 2 7v vw sw :2 w 4 2v 35V g 50 Homes “W E W 40 Run vm an V = 3 mm m w J3 T T 11:25sz In ‘MURATA LOHSZCNZRZMSS m ‘ nu mu m “1va0 mum JHKSVEBJWGML OUTPUT CURRENT 0"” 'wvo mum JMKZIZEJHSMG mm Figure 73 me 7h mu an WA 4 “V Vw 5w $05“; 3“ ma 2v CW . M LTCGADEB45 V cm mm 5 an _ z err 5 5n END autumn E 43 2 : ‘MURATA Luuazcmznzmaa 3n “mm VUDEN CERAMICJMmamsMG mum VUDEN CERAMICJMKBVEBJVDEML 20 m u I w n: mu m 0mm CURRENT (mA) “WWW m _m L7LJCUW
13
LTC34 0 6B
3406bfa
APPLICATIO S I FOR ATIO
WUUU
For the feedback resistors, choose R1 = 316k. R2 can
then be calculated from equation (2) to be:
RVRk
OUT
206 1 1 1000=
=
.
V
IN
C
IN
4.7µF
CER
V
IN
2.7V
TO 4.2V
LTC3406B
RUN
32.2µH*
22pF
1M
316k
3406B F07a
5
4
1
2
SW
V
FB
GND
C
OUT
**
10µF
CER
V
OUT
2.5V
*MURATA LQH32CN2R2M33
** TAIYO YUDEN JHK316BJ106ML
TAIYO YUDEN JMK212BJ475MG
Figure 7a Figure 7b
Figure 7 shows the complete circuit along with its effi-
ciency curve.
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10 1000
100
90
80
70
60
50
40
30
20
10
3406B F07b
1 100
V
OUT
= 2.5V
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
TYPICAL APPLICATIO S
U
V
IN
C
IN
**
4.7µF
CER
V
IN
2.7V
TO 4.2V LTC3406B-1.5
RUN
32.2µH*
3406B TA05
5
4
1
2
SW
V
OUT
GND
C
OUT1
10µF
CER
V
OUT
1.5V
*
**
MURATA LQH32CN2R2M33
TAIYO YUDEN CERAMIC JMK212BJ475MG
TAIYO YUDEN CERAMIC JMK316BJ106ML
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10 1000
100
90
80
70
60
50
40
30
20
10
3406B TA06
1 100
V
OUT
= 1.5V
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.5V
ILOAD = 200mA TO 600mA
3406B TA08
Efficiency vs Output Current
Load Step
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.5V
ILOAD = 0mA TO 600mA
3406B TA07
Load Step
Single Li-Ion 1.5V/600mA Regulator for
High Efficiency and Small Footprint
I00 22w V VIN sw 102%] 9° 0 M an L'maaoen 0“ 70 RUN v” END 30w g 50 3qu ‘MURATALDHSZCNZRZMSS 5 50 J3 “TAIVOVUDENJHKSIEBJIDEML E 2mm. 'TAIVOVUDENJMKZIZBJMEMG w 40 an 20 IO U] I In Inc In OUTPUT CURRENT (mA) fl» / “ML "I”"LW 1 4 LTLJFJW
14
LTC34 0 6B
3406bfa
TYPICAL APPLICATIO S
U
Single Li-Ion 1.2V/600mA Regulator for
High Efficiency and Small Footprint
VIN
CIN
4.7µF
CER
VIN
2.7V
TO 4.2V
LTC3406B
RUN
32.2µH*
22pF
301k
301k
3406B TA09
5
4
1
2
SW
VFB
GND
COUT**
10µF
CER
VOUT
1.2V
*MURATA LQH32CN2R2M33
** TAIYO YUDEN JHK316BJ106ML
TAIYO YUDEN JMK212BJ475MG
OUTPUT CURRENT (mA)
0.1
EFFICIENCY (%)
10 1000
100
90
80
70
60
50
40
30
20
10
3406B TA10
1 100
V
OUT
= 1.2V
VIN = 2.7V
VIN = 4.2V
VIN = 3.6V
Efficiency vs Output Current
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.2V
ILOAD = 200mA TO 600mA
3406B TA12
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
20µs/DIV
VIN = 3.6V
VOUT = 1.2V
ILOAD = 0mA TO 600mA
3406B TA11
Load StepLoad Step
L7LJCUW I‘VE SESMAX 7+7 Lflif N DATUM ‘A 3‘ L7 03070st REF NOTE \ DLMENSLCNS ARE m MLLLLMETERS 2 DRAWWG NOT TO SCALE 3 DLMENSLCNS ARE LMCLUSIVECFPLATING 4 DLMENSLCNS ARE EXCLUSLVE 0F MDLD FLASH AND M 5 MOLD FLASH SHALL NOT EXCEED 0 254mm 5 JEDEC PACKAGE REFERENCE Ls M0493 020 £50 A 7 mlmmalmn mmsRea by Lmeav Tecnnnlagy Comammn L5 maven m be mums and vehame Hnwevev nu LesDansmey .s assumed my us use Lmeav Tecnnnlagy Corpavatmn makes nu vepvesanr mmnmazmemtmunnmmnamsmmmsaasmneaRemnwunmmnmqenuamsungpamnmqm »
15
LTC34 0 6B
3406bfa
U
PACKAGE DESCRIPTIO
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3)
S5 TSOT-23 0302
PIN ONE
2.90 BSC
(NOTE 4)
0.95 BSC
1.90 BSC
0.80 – 0.90
1.00 MAX
0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX
0.62
MAX
0.95
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
.||— LINE/Ag LTW
16
LTC34 0 6B
3406bfa
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LT1616 500mA (I
OUT
), 1.4MHz, High Efficiency Step-Down 90% Efficiency, V
IN
= 3.6V to 25V, V
OUT
= 1.25V, I
Q
= 1.9mA,
DC/DC Converter I
SD
= <1µA, ThinSOT Package
LT1676 450mA (I
OUT
), 100kHz, High Efficiency Step-Down 90% Efficiency, V
IN
= 7.4V to 60V, V
OUT
= 1.24V, I
Q
= 3.2mA,
DC/DC Converter I
SD
= 2.5µA, S8 Package
LTC1701/LT1701B 750mA (I
OUT
), 1MHz, High Efficiency Step-Down 90% Efficiency, V
IN
= 2.5V to 5V, V
OUT
= 1.25V, I
Q
= 135µA,
DC/DC Converter I
SD
= <1µA, ThinSOT Package
LT1776 500mA (I
OUT
), 200kHz, High Efficiency Step-Down 90% Efficiency, V
IN
= 7.4V to 40V, V
OUT
= 1.24V, I
Q
= 3.2mA,
DC/DC Converter I
SD
= 30µA, N8, S8 Packages
LTC1877 600mA (I
OUT
), 550kHz, Synchronous Step-Down 95% Efficiency, V
IN
= 2.7V to 10V, V
OUT
= 0.8V, I
Q
= 10µA,
DC/DC Converter I
SD
= <1µA, MS8 Package
LTC1878 600mA (I
OUT
), 550kHz, Synchronous Step-Down 95% Efficiency, V
IN
= 2.7V to 6V, V
OUT
= 0.8V, I
Q
= 10µA,
DC/DC Converter I
SD
= <1µA, MS8 Package
LTC1879 1.2A (I
OUT
), 550kHz, Synchronous Step-Down 95% Efficiency, V
IN
= 2.7V to 10V, V
OUT
= 0.8V, I
Q
= 15µA,
DC/DC Converter I
SD
= <1µA, TSSOP-16 Package
LTC3403 600mA (I
OUT
), 1.5MHz, Synchronous Step-Down 96% Efficiency, V
IN
= 2.5V to 5.5V, V
OUT
= Dynamically Adjustable,
DC/DC Converter with Bypass Transistor I
Q
= 20µA, I
SD
= <1µA, DFN Package
LTC3404 600mA (I
OUT
), 1.4MHz, Synchronous Step-Down 95% Efficiency, V
IN
= 2.7V to 6V, V
OUT
= 0.8V, I
Q
= 10µA,
DC/DC Converter I
SD
= <1µA, MS8 Package
LTC3405/LTC3405A 300mA (I
OUT
), 1.5MHz, Synchronous Step-Down 96% Efficiency, V
IN
= 2.5V to 5.5V, V
OUT
= 0.8V, I
Q
= 20µA,
DC/DC Converter I
SD
= <1µA, ThinSOT Package
LTC3406 600mA (I
OUT
), 1.5MHz, Synchronous Step-Down 96% Efficiency, V
IN
= 2.5V to 5.5V, V
OUT
= 0.6V, I
Q
= 20µA,
DC/DC Converter I
SD
= <1µA, ThinSOT Package
LTC3411 1.25A (I
OUT
), 4MHz, Synchronous Step-Down 95% Efficiency, V
IN
= 2.5V to 5.5V, V
OUT
= 0.8V, I
Q
= 60µA,
DC/DC Converter I
SD
= <1µA, MS Package
LTC3412 2.5A (I
OUT
), 4MHz, Synchronous Step-Down 95% Efficiency, V
IN
= 2.5V to 5.5V, V
OUT
= 0.8V, I
Q
= 60µA,
DC/DC Converter I
SD
= <1µA, TSSOP-16E Package
LTC3440 600mA (I
OUT
), 2MHz, Synchronous Buck-Boost 95% Efficiency, V
IN
= 2.5V to 5.5V, V
OUT
= 2.5V, I
Q
= 25µA,
DC/DC Converter I
SD
= <1µA, MS Package
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
FAX: (408) 434-0507
www.linear.com
LT/TP 0604 1K REV A • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2002
U
TYPICAL APPLICATIO
V
IN
C
IN
4.7µF
CER
V
IN
5V
LTC3406B
RUN
32.2µH*
22pF
1M
221k
3406B TA13
5
4
1
2
SW
V
FB
GND
C
OUT
**
10µF
CER
V
OUT
3.3V
*MURATA LQH32CN2R2M33
** TAIYO YUDEN JHK316BJ106ML
TAIYO YUDEN JMK212BJ475MG
5V Input to 3.3V/0.6A Regulator

Products related to this Datasheet

IC REG BUCK ADJ 600MA TSOT23-5
IC REG BUCK ADJ 0.6A SYNC TSOT23
IC REG BUCK ADJ 600MA TSOT23-5
IC REG BUCK 1.8V 600MA TSOT23-5
IC REG BUCK 1.8V 600MA TSOT23-5
BOARD EVAL FOR LTC3406BES5
BOARD EVAL FOR LTC3406BES5
IC REG BUCK 1.5V 600MA TSOT23-5
IC REG BUCK 1.8V 600MA TSOT23-5
IC REG BUCK 1.5V 600MA TSOT23-5
IC REG BUCK ADJ 600MA TSOT23-5
IC REG BUCK 1.5V 600MA TSOT23-5
IC REG BUCK ADJ 600MA TSOT23-5
IC REG BUCK 1.5V 600MA TSOT23-5
IC REG BUCK 1.8V 600MA TSOT23-5
IC REG BUCK ADJ 0.6A SYNC TSOT23