LTC3427 [Linear]
500mA, 1.25MHz Synchronous Step-Up DC/DC Converter in 2mm × 2mm DFN Package; 采用2mm × 2mm DFN封装500毫安， 1.25MHz的同步升压型DC / DC转换器
| 型号： | LTC3427 |
| 厂家： | 
Linear |
| 描述： | 500mA, 1.25MHz Synchronous Step-Up DC/DC Converter in 2mm × 2mm DFN Package |
| 文件： | 总12页 (文件大小：200K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC3427
500mA, 1.25MHz
Synchronous Step-Up
DC/DC Converter in
2mm × 2mm DFN Package
U
FEATURES
DESCRIPTIO
The LTC®3427 is the industry’s first high efficiency, fixed
frequency, step-up DC/DC converter with true output
disconnect in a 6-lead 2mm × 2mm DFN package. Requir-
ing minimal external components, the LTC3427 operates
from an input voltage as low as 1.8V. The LTC3427
contains an internal 0.525Ω N-channel MOSFET switch
and a 0.575Ω P-channel MOSFET synchronous rectifier,
which enables it to supply 200mA at 3.3V from a 2-cell
alkaline battery input.
■
High Efficiency: Up to 94%
■
3.3V at 200mA from Two Alkaline Cells
■
5V at 200mA from a Single Li-Ion Cell
■
Inrush Current Limiting and Soft-Start
■
Output Disconnect in Shutdown
■
1.8V to 5V VIN Range
■
1.8V to 5.25V VOUT Range
■
1.25MHz Fixed Frequency, Low Noise PWM
■
Internal Synchronous Rectifier
■
Logic Controlled Shutdown (<1µA)
The LTC3427 limits inrush current during start-up and
provides a soft-start of VOUT. A switching frequency of
1.25MHz minimizes solution footprint by allowing the use
of tiny, low profile inductors and ceramic capacitors and
produces very low VOUT ripple. The current mode PWM
design is internally compensated, reducing external parts
count. Anti-ringing control reduces EMI in discontinuous
mode operation. The LTC3427 also features low shut-
down current of under 1µA and thermal shutdown.
■
Anti-Ringing Control Minimizes EMI
■
Tiny External Components
■
Short-Circuit Protection
■
Low Profile (0.75mm × 2mm × 2mm) DFN Package
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APPLICATIO S
■
Handheld Instruments
■
Digital Cameras
■
Wireless Handsets
GPS Receivers
Portable Medical Devices
MP3 Players
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
■
■
■
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TYPICAL APPLICATIO
2.4V to 3.3V Efficiency
2-Cell Alkaline to 3.3V Synchronous Boost Converter
100
95
90
85
80
75
70
1000
100
10
4.7µH
V
IN
1.8V TO 3.2V
EFFICIENCY
+
2-CELL
ALKALINE
2.2µF
V
SW
IN
LTC3427
V
OUT
3.3V
OFF ON
SHDN
V
OUT
FB
200mA
1000k
604k
POWER LOSS
4.7µF
GND
10
100
1000
3427 TA01a
LOAD CURRENT (mA)
3427 TA01b
3427fa
1
LTC3427
W W
U W
U W
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ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
VIN, VOUT Voltages ...................................... –0.3V to 6V
SHDN, FB Voltages ..................................... –0.3V to 6V
SW Voltage
DC .......................................................... –0.3V to 6V
Pulsed < 100ns ...................................... –0.3V to 7V
Operating Temperature Range
6
5
7
2
4
3
1
(Notes 2, 5) ............................................ –40°C to 85°C
Storage Temperature Range ................ –65°C to 125°C
DC PACKAGE
6-LEAD (2mm × 2mm) PLASTIC DFN
TJMAX = 125°C, θJA = 60°C/W TO 85°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
DC PART MARKING
LBSY
LTC3427EDC
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
IN
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V
= 2.4V, V
= 3.3V unless otherwise specified.
OUT
PARAMETER
CONDITIONS
MIN
TYP
MAX
1.8
5.25
1.265
50
UNITS
V
Minimum Start-Up Voltage
Output Voltage Adjust Range
Feedback Voltage
I
< 1mA
●
●
●
1.6
LOAD
1.8
V
1.215
1.24
1
V
Feedback Input Current
Quiescent Current—Shutdown
Quiescent Current—Active
NMOS Switch Leakage
PMOS Switch Leakage
NMOS Switch-On Resistance
PMOS Switch-On Resistance
NMOS Current Limit
V
V
V
= 1.24V
nA
µA
µA
µA
µA
Ω
FB
= 0V, V
= 0V
0.01
350
0.1
1
SHDN
OUT
= 1.5V (Note 3)
550
5
FB
0.1
5
0.525
0.575
Ω
●
500
80
mA
ns
%
Current Limit Delay to Output
Maximum Duty Cycle
Minimum Duty Cycle
Frequency
(Note 4)
40
87
V
V
= 1V
●
●
●
FB
FB
= 1.5V
0
%
0.9
1
1.25
1.5
MHz
V
SHDN Input High
SHDN Input Low
0.35
1
V
SHDN Input Current
V
= 5.5V
0.01
2
µA
ms
SHDN
Soft-Start Time
3427fa
2
LTC3427
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 4: Specification is guaranteed by design and not 100% tested in
production.
Note 5: The LTC3427 includes an overtemperature shutdown that is
intended to protect the device during momentary overload conditions.
Junction temperature will exceed 125°C when the overtemperature
shutdown is active. Continuous operation above the specified maximum
operating junction temperature may impair device reliability.
Note 2: The LTC3427E 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: Current is measured into the V
bootstrapped to the output. The current will reflect to the input supply by:
pin since the supply current is
OUT
(V /V ) • Efficiency. The outputs are not switching.
OUT IN
U W
TYPICAL PERFOR A CE CHARACTERISTICS
T = 25°C unless otherwise specified.
A
2-Cell Alkaline to 3.3V Efficiency
2-Cell Alkaline to 5V Efficiency
Li-Ion to 5V Efficiency
100
95
100
95
100
95
V
= 4.2V
V
= 3.1V
IN
IN
90
90
90
V
= 3.6V
V
= 3.2V
V
= 2.4V
IN
IN
IN
85
85
85
V
= 2.4V
IN
80
75
80
75
80
75
V
= 1.8V
V
= 3.1V
IN
IN
V
= 1.8V
IN
70
65
60
55
50
70
65
60
55
50
70
65
60
55
50
1
10
100
1000
1
10
100
1000
1
10
100
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
3427 G02
3427 G03
3427 G01
Inrush Current Control
Load Transient Response
V
Ripple, AC Coupled
OUT
V
OUT
I
LOAD
100mV/DIV
V
100mA
OUT
AC COUPLED
1V/DIV
I
LOAD
I
OUT
50mA
INDUCTOR
CURRENT
100mA/DIV
40mA
I
LOAD
TO 100mA
10mA
3427 G13
SHDN
5V/DIV
V
V
= 2.4V
500ns/DIV
IN
OUT
= 3.3V
3427 G05
3427 G04
L = 4.7µH
V
V
C
= 1.8V
100µs/DIV
V
C
= 2.4V
500µs/DIV
IN
IN
OUT
C
= 2.2µF
= 4.7µF
OUT
= 3.3V
= 22µF
IN
OUT
OUT
C
= 4.7µF
L = 4.7µH
L = 4.7µH
3427fa
3
LTC3427
TYPICAL PERFOR A CE CHARACTERISTICS T = 25°C unless otherwise specified.
U W
A
FB Voltage vs Temperature
Efficiency vs V
IN
Current Limit
0.90
0.80
0.70
0.60
0.50
100
90
80
70
60
50
40
1.25
1.24
1.23
V
V
= 2.4V
V
V
= 2.4V
IN
OUT
V
I
= 3.3V
= 100mA
IN
OUT
OUT
OUT
= 3.3V
= 3.3V
V
> V
OUT
IN
PMOS LDO MODE
–45 –30 –15
0
15 30 45 60 75 90
–45 –30 –15
0
15 30 45 60 75 90
1.5
2.5
3.5
(V)
4.5
TEMPERATURE (°C)
TEMPERATURE (°C)
V
IN
3427 G06
3427 G07
3427 G08
Frequency Accuracy
vs Temperature
SW Pin Anti-Ringing Operation
1.35
1.30
1.25
1.20
1.15
V
V
= 2.4V
IN
OUT
= 3.3V
INDUCTOR
CURRENT
50mA/DIV
SW
2V/DIV
3427 G10
V
V
C
= 1.8V
200ns/DIV
IN
= 3.3V
OUT
OUT
= 4.7µF
L = 4.7µH
–45 –30 –15
0
15 30 45 60 75 90
TEMPERATURE (°C)
3427 G09
R
vs Temperature
V
Supply Current (No Load)
DS(ON)
IN
0.45
0.40
0.35
0.30
0.70
V
V
= 2.4V
= 3.3V
T
A
V
= 25°C
IN
OUT
= V
= V
OUT FB
IN
0.65
0.60
PMOS
0.55
0.50
NMOS
0.45
0.40
0.35
–45 –30 –15
0
15 30 45 60 75 90
1.5
2.5
3.5
(V)
4.5
5.5
TEMPERATURE (°C)
V
IN
3427 G11
3427 G12
3427fa
4
LTC3427
U
U
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PI FU CTIO S
SW (Pin 1): Switch Pin for the Inductor Connection.
Minimize trace length between SW and the inductor. For
discontinuous inductor current, an internal 200Ω imped-
ance is connected from SW to VIN to eliminate high
frequency ringing, reducing EMI radiation.
FB (Pin 5): Feedback Input to the Error Amplifier. Connect
resistor divider tap to this pin. Referring to the Block
Diagram, VOUT can be adjusted from 1.8V to 5.25V by:
R1
R2
⎛
⎝
⎞
VOUT = 1.24V • 1+
⎜
⎟
⎠
GND (Pin 2): Signal and Power Ground. Provide a short,
direct PCB path between GND and the (–) side of the input
and output capacitor(s).
VOUT (Pin 6): Output Voltage Sense Input and Drain of the
Internal Synchronous Rectifier MOSFET. Driver bias is
derived from VOUT. PCB trace length from VOUT to the
output filter capacitor(s) should be as short and wide as
possible.
VIN (Pin 3): Input Supply Voltage. Connect VIN to the input
supply and decouple with a 2.2µF or larger ceramic
capacitor as close to VIN as possible.
SHDN (Pin 4): Shutdown Input. Less than 350mV on
SHDN shuts down the LTC3427. Placing 1V or more on
SHDN enables the LTC3427.
Exposed Pad (Pin 7): Ground for the LTC3427. This pin
must be soldered to the PCB ground plane for electrical
connection and rated thermal performance.
W
BLOCK DIAGRA
L1
4.7µH
OPTIONAL
V
IN
1.8V TO 5V
+
C
IN
2.2µF
4
3
1
V
IN
SW
BULK CONTROL
SIGNALS
SHDN
V
IN
ANTIRING
V
OUT
V
OUT
1.8V TO 5.25V
SHUTDOWN
AND
6
SHDN
V
BIAS
PWM
LOGIC
AND
+
–
DRIVERS
IZERO
COMP
CURRENT
SENSE
1.24V
1V
REFERENCE
PWM
COMP
–
– +
GAIN ERROR
AMPLIFIER
R1
R2
THERMAL
SHUTDOWN
FB
C
OUT
4.7µF
+
–
5
+
1.24V
Σ
I
LIM
REF
+
SLOPE COMPENSATION
START-UP
SOFT-START
OSCILLATOR
GND
2
EXPOSED PAD
7
3427 BD
3427fa
5
LTC3427
U
(Refer to Block Diagram)
OPERATIO
of input or output voltage. The current signal is blanked for
approximately 25ns to enhance noise rejection.
LOW NOISE FIXED FREQUENCY OPERATION
Shutdown
Current Limit
The LTC3427 is shut down by pulling the SHDN pin below
0.35V, and activated by pulling the SHDN pin above 1V.
Note that SHDN can be driven above VIN or VOUT as long
as it is limited to less than the absolute maximum rating.
The current limit circuitry shuts off the internal N-channel
MOSFETswitchwhenthecurrentlimitthresholdisreached.
The current limit comparator delay to output is typically
40ns.
Soft-Start
Zero Current Comparator
The LTC3427 provides soft-start by ramping the peak
inductorcurrentfromzerotoitspeakvalueof500mA. The
soft-start time is typically 2ms. A soft-start cycle is re-
initiated in the event of a commanded shutdown or a
thermal shutdown.
The zero current comparator monitors the inductor cur-
rent to the output and shuts off the synchronous rectifier
once this current reduces to approximately 20mA.
Anti-Ringing Control
Oscillator
The anti-ringing control connects a resistor across the
inductor to damp the ringing on the SW pin in discontinu-
ous conduction mode. The LCSW ringing (L = Inductor,
CSW = capacitance on the SW pin) is low energy, but can
cause EMI radiation.
The frequency of operation is set by an internal oscillator
to 1.25MHz for the LTC3427.
Error Amplifier
The error amplifier is a transconductance type with its
positive input internally connected to the 1.24V reference
and the negative input connected to FB. Internal clamps
limit the minimum and maximum error amplifier output
voltage for improved large-signal transient response.
Power converter control loop compensation is provided
internally by the error amplifier. A voltage divider from
VOUT to ground programs the output voltage via FB from
1.8V to 5.25V.
Output Disconnect and Inrush Limiting
The LTC3427 provides true output disconnect by elimi-
nating body diode conduction of the internal P-channel
MOSFET rectifier. This allows VOUT to go to zero volts
during shutdown without drawing any current from the
input source. It also provides inrush current limiting at
turn-on, minimizing surge currents seen by the input
supply. Note that to obtain the advantages of output
disconnect,theremustnotbeanyexternalSchottkydiode
R1
R2
⎛
⎝
⎞
connected between SW and VOUT
.
VOUT = 1.24V • 1+
⎜
⎟
⎠
Thermal Shutdown
The error amplifier also provides a soft-start feature
internal to the device.
If the die temperature reaches approximately 145°C, the
part will go into thermal shutdown. All switches will be
turned off. The device will be enabled and initiate a soft-
start sequence when the die temperature drops by
approximately 10°C.
Current Sensing
Lossless current sensing converts the peak current signal
of the N-channel MOSFET switch into a voltage that is
summed with the internal slope compensation. The
summedsignaliscomparedtotheerroramplifieroutputto
provideapeakcurrentcontrolcommandforthePWM.Peak
switch current is limited to 500mA minimum, independent
Note:DuetothehighfrequencyoperationoftheLTC3427,
board layout is extremely critical to minimize transients
due to stray inductance. Keep the output filter capacitor as
close as possible to the VOUT pin and use very low ESR/
ESL ceramic capacitors tied to a good ground plane.
3427fa
6
LTC3427
W U U
APPLICATIO S I FOR ATIO
U
LTC3427
SW
V
OUT
1
2
3
6
5
4
MINIMIZE
TRACE ON FB
GND
FB
V
SHDN
IN
+
V
IN
MULTIPLE VIAS
TO GROUND PLANE
3427 F01
Figure 1. Recommended Component Placement for a Single Layer Board. Traces Carrying High Current are Direct (GND, SW, V ,
IN
V
). Trace Area at FB is Kept Low. Lead Length to Battery Should be Kept Short. V and V
Ceramic Capacitors Should be as
OUT
IN
OUT
Close to the LTC3427 as Possible. A Multilayer Board with a Separate Ground Plane is Ideal, but not Absolutely Necessary
The inductor current ripple is typically set for 20% to 40%
of the maximum inductor current (IP). High frequency
ferrite core inductor materials reduce frequency depen-
dent power losses compared to cheaper powdered iron
types, improving efficiency. The inductor should have low
ESR (series resistance of the windings) to reduce the I2R
power losses, and must be able to handle the peak
inductor current without saturating. Molded chokes and
some chip inductors usually do not have enough core to
support the peak inductor currents of greater than 500mA
seen on the LTC3427. To minimize radiated noise, use a
toroid, pot core or shielded bobbin inductor. See Table 1
for suggested suppliers.
COMPONENT SELECTION
Inductor Selection
The LTC3427 can utilize small surface mount and chip
inductors due to its fast 1.25MHz switching frequency. A
minimum inductance value of 3.3µH is necessary for 3.6V
and lower voltage applications and a 4.7µH for output
voltages greater than 3.6V. Larger values of inductance
will allow greater output current capability by reducing the
inductor ripple current. Increasing the inductance above
10µH will increase size while providing little improvement
in output current capability.
The approximate output current capability of the LTC3427
vs Inductance value is given below in Equation 1 and
illustrated graphically in Figure 2.
Output and Input Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used to minimize the output voltage ripple. Multilayer
ceramic capacitors are an excellent choice as they have
extremely low ESR and are available in small footprints. A
2.2µF to 10µF output capacitor is sufficient for most
applications. Larger values up to 22µF may be used to
obtain extremely low output voltage ripple and improve
transient response. An additional phase lead capacitor
mayberequiredwithoutputcapacitorslargerthan10µFto
maintain acceptable phase margin. X5R and X7R dielec-
tric materials are preferred for their ability to maintain
capacitance over wide voltage and temperature ranges.
V •D
f •L • 2
⎛
⎞
IN
IOUT(MAX) = n • IP –
• 1–D
(
)
⎜
⎟
⎠
(1)
⎝
where:
n = estimated efficiency
IP = peak current limit value (0.5A min)
VIN = input (battery) voltage
D = steady-state duty ratio = (VOUT – VIN)/VOUT
f = switching frequency (1.25MHz typical)
L = inductance value
3427fa
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LTC3427
W U U
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APPLICATIO S I FOR ATIO
Table 1. Inductor Vendor Information
SUPPLIER
PHONE
FAX
WEBSITE
Murata
USA: (814) 237-1431
(800) 831-9172
USA: (814) 238-0490
www.murata.com
Sumida
USA: (847) 956-0666
Japan: 81-3-3607-5111
USA: (847) 956-0702
Japan: 81-3-3607-5144
www.sumida.com
Coilcraft
(847) 639-6400
(800) 227-7040
(847) 639-1469
(650) 361-2508
www.coilcraft.com
CoEv Magnetics
www.circuitprotection.com/magnetics.asp
TDK
(847) 803-6100
(847) 297-0070
(201) 785-8800
(847) 803-6296
(847) 669-7864
(201) 785-8810
www.component.tdk.com
www.toko.com
TOKO
Wurth
www.we-online.com
0.280
Table 2. Capacitor Vendor Information
SUPPLIER PHONE FAX
1.8V TO 3V
3.1V TO 5V
0.260
0.240
0.220
0.200
0.180
0.160
0.140
0.120
0.100
WEBSITE
1.8V TO 3.3V
AVX
(803) 448-9411 (803) 448-1943 www.avxcorp.com
(619) 661-6322 (619) 661-1055 www.sanyovideo.com
Sanyo
1.8V TO 3.6V
TDK
(847) 803-6100 (847) 803-629
USA: USA:
www.component.
tdk.com
1.8V TO 5V
Murata
www.murata.com
(814) 237-1431 (814) 238-0490
(800) 831-9172
Taiyo
(408) 573-4150 (408) 573-4159 www.t-yuden.com
3
5
7
9
11 13
23
15 17 19 21
Yuden
INDUCTANCE (µH)
3427 F02
Figure 2. Maximum Output Current vs
Inductance Based on 90% Efficiency
Thermal Considerations
To deliver the power that the LTC3427 is capable of, it is
imperative that a good thermal path be provided to dissi-
pate the heat generated within the package. This can be
accomplished by taking advantage of the large thermal
pad on the underside of the LTC3427. It is recommended
that multiple vias in the printed circuit board be used to
conduct heat away from the LTC3427 and into the copper
plane with as much area as possible. In the event that the
junction temperature gets too high, the LTC3427 will go
into thermal shutdown and all switching will stop until the
internaltemperaturedropsatwhichpointasoft-startcycle
will be initiated.
Low ESR input capacitors reduce input switching noise
and reduce the peak current drawn from the battery. It
follows that ceramic capacitors are also a good choice for
input decoupling and should be located as close as pos-
sible to the device. A 2.2µF input capacitor is sufficient for
virtually any application. Larger values may be used with-
out limitations. Table 2 shows a list of several ceramic
capacitor manufacturers. Consult the manufacturers di-
rectly for detailed information on their entire selection of
ceramic capacitors.
3427fa
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LTC3427
W U U
APPLICATIO S I FOR ATIO
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VIN > VOUT Operation
Short-Circuit Protection
The LTC3427 will maintain voltage regulation when the
input voltage is above the output voltage. This is achieved
by terminating the switching of the synchronous P-chan-
nel MOSFET and applying VIN statically on its gate. This
will ensure the volt • seconds across the inductor reverse
during the time current is flowing to the output. Since this
mode will dissipate more power in the LTC3427, the
maximum output current is limited in order to maintain an
acceptable junction temperature and is given by:
The LTC3427 output disconnect feature allows output
short circuit while maintaining a maximum internally set
current limit. However, the LTC3427 also incorporates
internal features such as current limit foldback and ther-
mal shutdown for protection from an excessive overload
or short circuit. During a prolonged short circuit the
current limit folds back to a typical value of approximately
400mA should VOUT drop below 950mV. This 400mA
current limit remains in effect until VOUT exceeds approxi-
mately 1V, at which time the nominally internally set
current limit is restored.
125 – TA
IOUT(MAX)
=
85 • V + 1.5 – V
⎡
⎤
(
)
IN
OUT
⎣
⎦
where TA = ambient temperature.
For example at VIN = 4.5V, VOUT = 3.3V, and TA = 85°C, the
maximum output current is 145mA.
3427fa
9
LTC3427
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TYPICAL APPLICATIO S
L1
4.7µH
2-Cell to 3.3V Efficiency
V
IN
100
95
1.8V TO 3.2V
+
2-CELL
ALKALINE
C
IN
2.2µF
V
= 3.1V
IN
90
V
SW
IN
V
= 2.4V
IN
85
LTC3427
V
OUT
80
75
3.3V
OFF ON
SHDN
V
OUT
FB
V
= 1.8V
IN
200mA
1000k
604k
C
OUT
4.7µF
70
65
60
55
50
GND
C
: TAIYO YUDEN X5R JMK212BJ225MD
OUT
IN
3427 F03a
C
: TAIYO YUDEN X5R JMK212BJ475MD
L1: TDK RLF7030T-4R7M3R4
1
10
100
1000
LOAD CURRENT (mA)
Figure 3. 2-Cell Alkaline to 3.3V Synchronous Boost Converter
3427 G01
L1
4.7µH
2-Cell to 5V Efficiency
V
IN
100
95
1.8V TO 3.2V
+
2-CELL
C
IN
2.2µF
ALKALINE
90
V
SW
IN
V
= 3.2V
IN
85
LTC3427
V
= 2.4V
V
IN
OUT
80
75
5V
OFF ON
SHDN
V
OUT
FB
150mA
1000k
332k
V
= 1.8V
IN
C
OUT
4.7µF
70
65
60
55
50
GND
C
OUT
: TAIYO YUDEN X5R JMK212BJ225MD
IN
3427 F04a
C
: TAIYO YUDEN X5R JMK212BJ475MD
L1: TDK RLF7030T-4R7M3R4
1
10
100
1000
LOAD CURRENT (mA)
Figure 4. 2-Cell Alkaline to 5V Synchronous
Boost Converter with Output Disconnect
3427 G03
Li-Ion to 5V Synchronous Boost Converter
Li-Ion to 5V Efficiency
100
95
L1
4.7µH
V
IN
V
= 4.2V
IN
3.1V TO 4.2V
90
+
C
V
= 3.6V
IN
Li-Ion
IN
2.2µF
85
V
SW
IN
80
75
V
= 3.1V
LTC3427
IN
V
OUT
5V
OFF ON
SHDN
V
OUT
FB
70
65
60
55
50
250mA
1000k
332k
C
OUT
GND
C
C
: TAIYO YUDEN X5R JMK212BJ225MD
IN
OUT
4.7µF
: TAIYO YUDEN X5R JMK212BJ475MD
L1: TDK RLF7030T-4R7M3R4
3427 TA02a
1
10
100
1000
LOAD CURRENT (mA)
3427 G02
3427fa
10
LTC3427
U
PACKAGE DESCRIPTIO
DC Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703)
0.675 ±0.05
2.50 ±0.05
0.61 ±0.05
1.15 ±0.05
(2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
1.42 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
0.56 ± 0.05
(2 SIDES)
0.38 ± 0.05
4
6
2.00 ±0.10
(4 SIDES)
PIN 1 BAR
PIN 1
TOP MARK
CHAMFER OF
(SEE NOTE 6)
EXPOSED PAD
(DC6) DFN 1103
3
1
0.25 ± 0.05
0.50 BSC
0.75 ±0.05
0.200 REF
1.37 ±0.05
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
3427fa
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-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LTC3427
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT®1613
800mA I , 1.4MHz, Step-Up DC/DC Converter
V : 1.1V to 10V, V
5-Lead SOT-23 Package
= 34V, I = 3mA, I < 1µA,
SW
IN
OUT(MAX) Q SD
LT1615
350mA I , Micropower, Step-Up DC/DC Converter
V : 1.2V to 15V, V
= 34V, I = 20µA, I < 1µA,
Q SD
SW
IN
OUT(MAX)
ThinSOTTM Package
LT1618
1.5A I , 1.4MHz, Constant Current/Constant Voltage
Step-Up DC/DC Converter
V : 1.6V to 18V, V
DFN, MSOP Packages
= 35V, I = 1.8mA, I < 1µA,
Q SD
SW
IN
OUT(MAX)
LT1930/LT1930A
1A I , 1.2MHz/2.2MHZ, Step-Up DC/DC Converters
V : 2.6V to 16V, V
ThinSOT Package
= 34V, I = 4.2mA/5.5mA, I < 1µA,
SW
IN
OUT(MAX)
Q
SD
LTC3400/LTC3400B 600mA I , 1.2MHz, Synchronous Step-Up
92% Efficiency V : 0.85V to 5V, V
= 5V, I = 19µA/300µA,
OUT(MAX) Q
SW
IN
DC/DC Converters
I
< 1µA, ThinSOT Package
SD
LTC3401
1A I , 3MHz, Synchronous Step-Up DC/DC Converter
97% Efficiency V : 0.5V to 5V, V
10-Lead MS Package
= 6V, I = 38µA, I < 1µA,
Q SD
SW
IN
OUT(MAX)
LTC3402
2A I , 3MHz, Synchronous Step-Up DC/DC Converter
97% Efficiency V : 0.5V to 5V, V
10-Lead MS Package
= 6V, I = 38µA, I < 1µA,
Q SD
SW
IN
OUT(MAX)
LTC3421
3A I , 3MHz, Synchronous Step-Up
DC/DC Converter with Output Disconnect
95% Efficiency V : 0.5V to 4.5V, V
= 5.25V, I = 12µA,
Q
SW
IN
OUT(MAX)
OUT(MAX)
OUT(MAX)
OUT(MAX)
I
< 1µA, QFN24 Package
SD
LTC3422
1.5A I , 3MHz Synchronous Step-Up
95% Efficiency V : 0.5V to 4.5V, V
= 5.25V, I = 25µA,
Q
SW
IN
DC/DC Converter with Output Disconnect
I
< 1µA, 3mm × 3mm DFN Package
SD
LTC3423/LTC3424
LTC3426
1A/2A I , 3MHz, Synchronous Step-Up DC/DC Converter 95% Efficiency V : 0.5V to 5.5V, V
= 5.5V, I = 38µA,
Q
SW
IN
I
< 1µA, 10-Lead MS Package
SD
2A I , 1.2MHz, Step-Up DC/DC Converter
92% Efficiency V : 1.6V to 4.3V, V
= 5V, I < 1µA,
SD
SW
IN
SOT-23 Package
LTC3428
500mA I , 1.25MHz/2.5MHz, Synchronous Step-Up
DC/DC Converters with Output Disconnect
92% Efficiency V : 1.8V to 5V, V
2mm × 2mm DFN Package
= 5.25V, I < 1µA,
OUT(MAX) SD
SW
IN
LTC3429
600mA I , 500kHz, Synchronous Step-Up DC/DC
Converter with Output Disconnect and Soft-Start
96% Efficiency V : 0.5V to 4.4V, V
= 5V, I = 20µA/300µA,
OUT(MAX) Q
SW
IN
I
< 1µA, ThinSOT Package
SD
LTC3458
1.4A I , 1.5MHz, Synchronous Step-Up DC/DC
Converter/Output Disconnect/Burst Mode Operation
93% Efficiency V : 1.5V to 6V, V
= 7.5V, I = 15µA,
OUT(MAX) Q
SW
IN
I
< 1µA, DFN12 Package
SD
LTC3458L
LTC3459
1.7A I , 1.5MHz, Synchronous Step-Up DC/DC Converter 94% Efficiency V
= 6V, I = 12µA, DFN12 Package
SW
OUT(MAX) Q
with Output Disconnect, Automatic Burst Mode® Operation
70mA I , 10V Micropower Synchronous Boost
V : 1.5V to 5.5V, V
ThinSOT Package
= 10V, I = 10µA, I < 1µA,
SW
IN
OUT(MAX)
Q
SD
Converter/Output Disconnect/Burst Mode Operation
LTC3525-3.3
LTC3525-5
400mA Micropower Synchronous Step-Up
DC/DC Converter with Output Disconnect
95% Efficiency V : 1V to 4.5V, V
= 3.3V or 5V, I = 7µA,
OUT(MAX) Q
IN
I
< 1µA, SC-70 Package
SD
ThinSOT is a trademark of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation.
3427fa
LT 0406 REV A • PRINTED IN THE USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005
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