LTC3459
10V Micropower
Synchronous Boost Converter
FEATURES
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DESCRIPTION
The LTC
®
3459 is a low current, high efficiency synchronous
boost converter intended for low power, size constrained
portable applications. The LTC3459 can be powered from
a single lithium ion battery, a 2- to 3-cell stack of alkaline
or nickel batteries, or any low impedance voltage source
between 1.5V and 5.5V. The output is programmable via
an external divider between 2.5V and 10V. Although the
part is primarily intended for boost applications, V
OUT
will
maintain regulation below V
IN
(at reduced efficiency).
The LTC3459 offers Burst Mode operation with a fixed
peak current, providing high conversion efficiency over
a wide range of load currents. During start-up, inductor
current is controlled preventing the inrush surge current
found in many boost converters. In shutdown the output
is disconnected from the input and quiescent current is
reduced to <1μA.
The LTC3459 is offered in low profile 6-pin 2mm
×
2mm
DFN, 2mm
×
3mm DFN or SOT-23 (ThinSOT
TM
) packages,
allowing a tiny footprint for the total solution.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Small Solution Size
>85% Efficiency over Wide Load Range
Internal Synchronous Rectifier
V
IN
Range: 1.5V to 5.5V
5V at 30mA from 3.3V Input
3.3V at 20mA from 2 AA Cell Input
Programmable Output Voltages Up to 10V
Burst Mode
®
Operation
Inrush Current Limiting
Output Disconnect in Shutdown
Ultralow Quiescent (10μA) and Shutdown (<1μA)
Currents
Low Profile 2mm
×
2mm DFN, 2mm
×
3mm DFN or
SOT-23 Package
APPLICATIONS
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General Purpose Micropower Boost
Digital Cameras
PDAs
LCD Bias
Small OLED Displays
Supercap Charging
TYPICAL APPLICATION
5V to 8V Converter
100
22μH
90
EFFICIENCY (%)
SW
5V
V
IN
V
OUT
2M
FB
365k
3459 TA01a
Efficiency
V
IN
= 5V
V
OUT
= 8V
LTC3459
1μF
OFF ON
SHDN
GND
47pF
4.7μF
V
OUT
8V
30mA
80
70
60
50
0.01
0.1
1
I
LOAD
(mA)
10
100
3459 TA01b
3459fc
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LTC3459
ABSOLUTE MAXIMUM RATINGS
Referred to GND (Note 1)
V
IN
, FB Voltage ........................................... –0.3V to 7V
V
OUT
,
SHDN
Voltage ................................. –0.3V to 10V
SW Voltage .............................................. –0.3V to 12V
Operating Temperature Range
(Notes 2, 3) ......................................... –40°C to 85°C
Storage Temperature Range.................. –65°C to 150°C
Reflow Temperature .............................................. 260°C
Lead Temperature, S6 Package
(Soldering, 10 sec) .......................................... 300°C
PIN CONFIGURATION
TOP VIEW
V
IN
1
V
OUT
2
SHDN
3
7
6 SW
5 GND
4 FB
SHDN
1
V
OUT
2
FB 3
7
TOP VIEW
TOP VIEW
6 V
IN
5 GND
4 SW
SW 1
GND 2
FB 3
6 V
IN
5 V
OUT
4
SHDN
DC PACKAGE
6-LEAD (2mm 2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 102°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
DCB PACKAGE
6-LEAD (2mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 64°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 192°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3459EDC#PBF
LTC3459EDCB#PBF
LTC3459ES6#PBF
TAPE AND REEL
LTC3459EDC#TRPBF
LTC3459EDCB#TRPBF
LTC3459ES6#TRPBF
PART MARKING
LDTG
LDMM
LTAHA
PACKAGE DESCRIPTION
Low Profile (2mm
×
2mm) Plastic DFN
Low Profile (2mm
×
3mm) Plastic DFN
Low Profile SOT-23
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3459fc
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LTC3459
ELECTRICAL CHARACTERISTICS
PARAMETER
V
IN
Input Voltage Range
V
IN
Quiescent Current
V
IN
Shutdown Current
V
OUT
Programmable Voltage Range
V
OUT
Quiescent Supply Current
V
OUT
Shutdown Current
Reference
Feedback Voltage
FB Input Leakage Current
Converter Performance
Peak Switch Current (V
IN
= 3.3V)
t
OFF
Timer (V
IN
= 3.3V, V
OUT
= 5V)
Zero Current Comparator Threshold
Main NMOS Switch
On-Resistance
Leakage Current
Main PMOS Switch
On-Resistance
Leakage Current
Logic Inputs
SHDN
Threshold (Rising Edge)
SHDN
Hysteresis
SHDN
Input Leakage Current
SHDN
= 3.3V
0.3
80
0
50
1
V
mV
nA
V
OUT
= 5V
V
IN
= 5V, V
SWITCH
= 5V, V
OUT
= 0V
4.2
0.02
2
Ω
μA
V
OUT
= 5V
V
SWITCH
= 10V, V
OUT
= 10V
2.8
0.01
1
Ω
μA
L = 22μH
Varies by 1/(V
OUT
– V
IN
)
L = 22μH
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.3V, V
OUT
= 5V, unless otherwise noted.
CONDITIONS
MIN
1.5
10
0.1
2.5
2
0.1
l
TYP
MAX
5.5
20
1
10
4
1
1.25
50
90
550
UNITS
V
μA
μA
V
μA
μA
V
nA
mA
ns
mA
SHDN
= V
CC
SHDN
= GND
SHDN
= V
CC
SHDN
= GND
V
IN
= 3.3V, V
OUT
= 7.5V
Measured on FB
60
225
1.19
1.22
10
75
400
0
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 2:
The LTC3459E is guaranteed to meet performance specifications
from 0°C to 85°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:
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.
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LTC3459
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum R
OUT
vs V
IN
4000
3500
3000
R
OUT
(Ω)
2500
2000
1500
1000
500
0
1.5
2
2.5
3
3.5
V
IN
(V)
3459 G01
(T
A
= 25°C, unless otherwise noted).
V
IN
and V
OUT
Quiescent Current
vs Temperature
16
V
IN
= 3.3V
14 V
OUT
= 5V
12
CURRENT (μA)
I
IN
10
8
6
4
2
0
–40
–20
0
I
OUT
Maximum P
OUT
vs V
IN
V
OUT
= 10V
V
OUT
= 7.5V
V
OUT
= 5V
V
OUT
= 3.3V
L = 22μH
P
OUT
(mW)
400
350
300
250
200
150
100
50
V
OUT
= 10V
V
OUT
= 7.5V
V
OUT
= 5V
V
OUT
= 3.3V
L = 22μH
4
4.5
5
5.5
0
1.5
2
2.5
3
3.5
V
IN
(V)
4
4.5
5
5.5
60
40
20
TEMPERATURE (°C)
80
3459 G03
3459 G02
Switching Frequency
vs V
IN
at Various V
OUTs
3.0
V
OUT
= 10V
V
OUT
= 7.5V
V
OUT
= 5V
V
OUT
= 3.3V
L = 22μH
2.0
1.5
% CHANGE IN V
OUT
1.0
0.5
0
–0.5
–1.0
V
OUT
Regulation vs V
IN
and C
OUT
6
4.7μF
10μF
22μF
47μF
V
OUT
= 5V
L = 22μH
5
N-Channel and P-Channel
MOSFET R
DS(ON)
vs Temperature
V
OUT
= 5V
2.5
FREQUENCY (MHz)
PCH
4
R
DS(ON)
(Ω)
NCH
3
2
1
2.0
1.5
1.0
–1.5
0.5
1.5
2
2.5
3
3.5
V
IN
(V)
3459 G04
4
4.5
5
5.5
–2.0
1.5
2
2.5
3
3.5
V
IN
(V)
4
4.5
5
5.5
0
–40
–20
40
20
60
0
TEMPERATURE (°C)
80
3459 G06
3459 G05
Shutdown Threshold Voltage
vs Temperature
1.2
SHUTDOWN THRESHOLD VOLTAGE (V)
1.0
SHDN RISING
0.8
SHDN FALLING
0.6
0.4
0.2
0
–40
INDUCTOR
CURRENT
50mA/DIV
SW
CURRENT
50mA/DIV
Burst Cycle
Switch Pin Waveform
SW
CURRENT
50mA/DIV
INDUCTOR
CURRENT
50mA/DIV
V
IN
= 3.3V
V
OUT
= 5V
L = 22μH
–20
40
20
60
0
TEMPERATURE (°C)
80
3459 G07
1μs/DIV
3459 G08
V
IN
= 3.3V
V
OUT
= 5V
L = 22μH
100ns/DIV
3459 G09
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LTC3459
TYPICAL PERFORMANCE CHARACTERISTICS
V
OUT
AC Ripple
V
OUT
50mV/DIV
(T
A
= 25°C, unless otherwise noted).
Burst Cycle
Burst Cycle
SW
CURRENT
50mA/DIV
SW
CURRENT
50mA/DIV
INDUCTOR
CURRENT
50mA/DIV
INDUCTOR
CURRENT
50mA/DIV
INDUCTOR
CURRENT
50mA/DIV
V
IN
= 5V
V
OUT
= 10V
L = 22μH
1μs/DIV
3459 G11
V
IN
= 3.3V
V
OUT
= 5V
L = 22μH
C
OUT
= 4.7μF
C
FF
= 47pF
5μs/DIV
3459 G10
V
IN
= 2V
V
OUT
= 10V
L = 22μH
1μs/DIV
3459 G12
V
OUT
Regulated Below
V
IN
Burst Cycle
Shorted Output
V
OUT
VOLTAGE
50mA/DIV
Start-Up
SW
CURRENT
50mA/DIV
INDUCTOR
CURRENT
50mA/DIV
SW
CURRENT
50mA/DIV
INDUCTOR
CURRENT
50mA/DIV
INPUT
CURRENT
50mA/DIV
V
IN
= 5V
V
OUT
= 0V
L = 22μH
500ns/DIV
3459 G14
V
IN
= 5V
V
OUT
= 3.5V
L = 22μH
1μs/DIV
3459 G13
250μs/DIV
V
IN
= 3.6V
V
OUT
= 0V TO 8V
L = 22μH
C
IN
= 2.2μF
3459 G15
Load Steps
Load Steps
V
OUT
AC RIPPLE
50mV/DIV
WITH 50kΩ
(TRACE 2
GROUNDED)
TO 500Ω
(TRACE 2 = 5V)
V
OUT
AC RIPPLE
50mV/DIV
WITH 5kΩ
(TRACE 2
GROUNDED)
TO 500Ω
(TRACE 2 = 5V)
V
IN
= 3.6V
V
OUT
= 8V
L = 22μH
C
OUT
= 4.7μF
C
FF
= 47pF
100μs/DIV
3459 G16
V
IN
= 3.6V
V
OUT
= 8V
L = 22μH
C
OUT
= 4.7μF
C
FF
= 47pF
100μs/DIV
3459 G17
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