LTC3525-3/
LTC3525-3.3/LTC3525-5
400mA Micropower
Synchronous Step-Up DC/DC
Converter with Output Disconnect
FEATURES
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DESCRIPTION
The LTC
®
3525-3/LTC3525-3.3/LTC3525-5 are high ef-
ficiency synchronous step-up DC/DC converters with
output disconnect that can start up with an input as low
as 1V. They offer a compact, high efficiency alternative to
charge pumps in single cell or dual cell alkaline or Li-Ion
applications. Only three small external components are
required. The LTC3525 is offered in fixed output voltages
of 3V, 3.3V or 5V.
The device includes a 0.5Ω N-channel MOSFET switch
and a 0.8Ω P-channel synchronous rectifier. Peak switch
current ranges from 150mA to 400mA, depending on
load, providing enhanced efficiency. Quiescent current
is an ultralow 7µA, maximizing battery life in portable
applications.
Other features include <1µA shutdown current, anti-
ringing control and thermal shutdown. The LTC3525 is
available in a tiny 6-pin SC70 package.
L,
LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Patents pending.
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Up to 95% Efficiency
Output Disconnect and Inrush Current Limit
Fixed Output Voltages of 3V, 3.3V or 5V
Delivers 65mA at 3V from a 1V Input
Delivers 60mA at 3.3V from a 1V Input,
or 140mA at 3.3V from a 1.8V Input
Delivers 175mA at 5V from a 3V Input
Burst Mode
®
Operation: I
Q
= 7µA
Only Three External Components
V
IN
> V
OUT
Operation
<1µA Shutdown Current
Antiringing Control
Short-Circuit and Overtemperature Protection
Very Low Profile of 1mm
Tiny 6-Pin SC70 Package
APPLICATIONS
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MP3 Players
Portable Instruments
Glucose Meters
Digital Cameras
TYPICAL APPLICATION
L1*
10µH
100
90
LTC3525-3.3
V
IN
OFF ON
1µF
SHDN
GND
SW
V
OUT
GND
V
OUT
3.3V
60mA
10µF
EFFICIENCY (%)
80
70
60
50
40
30
LTC3525-3.3 Efficiency and Power
Loss vs Load Current
100
10
EFFICIENCY
1
POWER LOSS (mW)
V
IN
1V TO 1.6V
POWER LOSS
0.1
V
IN
= 3V
V
IN
= 2.4V
V
IN
= 1.2V
0.1
1
10
LOAD (mA)
100
3525 TA01
*MURATA LQH32CN100K53
20
0.01
0.01
1000
LT3525 • TA02
3525fb
1
LTC3525-3/
LTC3525-3.3/LTC3525-5
(Note 1)
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
TOP VIEW
SHDN
1
GND
2
V
IN
3
6
SW
5
GND
4 V
OUT
V
IN
, V
OUT
Voltage ........................................ – 0.3V to 6V
SW Voltage ................................................. – 0.3V to 6V
SW Voltage < 100ns.................................... –0.3V to 7V
SHDN
Voltage ............................................. –0.3V to 6V
Operating Temperature Range
(Notes 2, 5) ..............................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 125°C
Lead Temperature (Soldering, 10 sec)................... 300°C
SC6 PACKAGE
6-LEAD PLASTIC SC70
T
JMAX
= 125°C
θ
JA
= 256°C/W IN FREE AIR,
θ
JA
= 150°C/W ON BOARD OVER GROUND PLANE
ORDER INFORMATION
LEAD FREE FINISH
LTC3525ESC6-3#PBF
LTC3525ESC6-3.3#PBF
LTC3525ESC6-5#PBF
TAPE AND REEL
LTC3525ESC6-3#TRPBF
LTC3525ESC6-5#TRPBF
PART MARKING
LCDR
LBWT
PACKAGE DESCRIPTION
6-Lead Plastic SC70
6-Lead Plastic SC70
6-Lead Plastic SC70
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
LTC3525ESC6-3.3#TRPBF LBTG
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/
(LTC3525-3)
The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 1.2V, V
SHDN
= 1.2V, V
OUT
= 3V unless otherwise noted.
PARAMETER
Input Start-Up Voltage
Output Voltage
Quiescent Current, V
OUT
Quiescent Current, V
IN
Quiescent Current, V
IN
– Shutdown
NMOS Switch Leakage Current
PMOS Switch Leakage Current
NMOS Switch On-Resistance
PMOS Switch On-Resistance
Peak Current Limit
SHDN
Threshold Voltage
SHDN
Input Current
V
SHDN
= V
IN
or V
OUT
(Note 6)
SHDN
= V
IN
(Note 4)
SHDN
= V
IN
(Note 4)
SHDN
= 0V, V
OUT
= 0V
Not Including Switch Leakage
V
IN
= V
OUT
= V
SW
= 5V,
SHDN
= 0V
V
IN
= V
SW
= 5V, V
OUT
= 0V,
SHDN
= 0V
(Note 3)
(Note 3)
0.4
0.4
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
2.91
TYP
0.85
3.00
7
0.5
0.1
0.1
0.1
0.6
0.9
0.45
0.6
0.01
MAX
1
3.09
15
3
1
1
3
UNITS
V
V
µA
µA
µA
µA
µA
Ω
Ω
A
1
1
V
µA
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LTC3525-3/
LTC3525-3.3/LTC3525-5
(LTC3525-3.3)
The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 1.2V, V
SHDN
= 1.2V, V
OUT
= 3.3V unless otherwise noted.
PARAMETER
Input Start-Up Voltage
Output Voltage
Quiescent Current, V
OUT
Quiescent Current, V
IN
Quiescent Current, V
IN
– Shutdown
NMOS Switch Leakage Current
PMOS Switch Leakage Current
NMOS Switch On-Resistance
PMOS Switch On-Resistance
Peak Current Limit
SHDN
Threshold Voltage
SHDN
Input Current
V
SHDN
= V
IN
or V
OUT
(Note 6)
SHDN
= V
IN
(Note 4)
SHDN
= V
IN
(Note 4)
SHDN
= 0V, V
OUT
= 0V
Not Including Switch Leakage
V
IN
= V
OUT
= V
SW
= 5V,
SHDN
= 0V
V
IN
= V
SW
= 5V, V
OUT
= 0V,
SHDN
= 0V
(Note 3)
(Note 3)
0.4
0.4
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
3.20
TYP
0.85
3.30
7
0.5
0.1
0.1
0.1
0.5
0.8
0.45
0.6
0.01
MAX
1
3.40
15
3
1
1
3
UNITS
V
V
µA
µA
µA
µA
µA
Ω
Ω
A
1
1
V
µA
(LTC3525-5)
The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 2.4V, V
SHDN
= 2.4V, V
OUT
= 5V unless otherwise noted.
PARAMETER
Input Start-Up Voltage
Output Voltage
Quiescent Current, V
OUT
Quiescent Current, V
IN
Quiescent Current, V
IN
– Shutdown
NMOS Switch Leakage Current
PMOS Switch Leakage Current
NMOS Switch On-Resistance
PMOS Switch On-Resistance
Peak Current Limit
SHDN
Threshold Voltage
SHDN
Input Current
V
SHDN
= V
IN
or V
OUT
(Note 6)
SHDN
= V
IN
(Note 4)
SHDN
= V
IN
(Note 4)
SHDN
= 0V, V
OUT
= 0V
Not Including Switch Leakage
V
IN
= V
OUT
= V
SW
= 5V,
SHDN
= 0V
V
IN
= V
SW
= 5V, V
OUT
= 0V,
SHDN
= 0V
(Note 3)
(Note 3)
0.4
0.4
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CONDITIONS
MIN
4.85
TYP
0.85
5.00
8
1.5
0.1
0.1
0.1
0.4
0.7
0.5
0.6
0.01
MAX
1
5.15
18
5
1
1
3
UNITS
V
V
µA
µA
µA
µA
µA
Ω
Ω
A
1
1
V
µA
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 LTC3525E 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:
Specification is guaranteed by design and not 100% tested in
production.
Note 4:
Current Measurements are performed when the LTC3525 is not
switching.
Note 5:
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.
Note 6:
Consult LTC Marketing for other output voltage options.
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LTC3525-3/
LTC3525-3.3/LTC3525-5
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C unless otherwise noted.
300
250
200
I
OUT
(mA)
150
100
50
0
0.5
50
LTC3525-3
LTC3525-5
LOAD (mA)
Maximum Output Current vs V
IN
(for V
OUT
to Drop 2.5%)
LTC3525-3.3
Maximum Startup Load vs V
IN
(Resistive Load)
250
200
LTC3525-5
50
45
40
35
I
IN
(µA)
150
100
LTC3525-3.3
30
25
20
15
10
5
No-Load Input Current vs V
IN
LTC3525-5
LTC3525-3
LTC3525-3.3
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
0
0.5
1.0
1.5
2.0
V
IN
(V)
2.5
3.0
3525 G02
0
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
3525 G01
3525 G03
LTC3525-3 Efficiency and Power
Loss vs Load
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
0.01
0.1
1
10
LOAD (mA)
V
IN
= 2.4V
V
IN
= 1.2V
100
0.1
EFFICIENCY
1
10
POWER LOSS (mW)
100
100
90
80
EFFICIENCY (%)
70
60
50
40
30
LTC3525-3.3 Efficiency and Power
Loss vs Load
100
100
90
10
EFFICIENCY
1
80
EFFICIENCY (%)
70
60
50
40
30
20
10
LTC3525-5 Efficiency and Power
Loss vs Load
1000
100
EFFICIENCY
10
POWER LOSS
POWER LOSS (mW)
POWER LOSS (mW)
POWER LOSS
POWER LOSS
1
0.1
V
IN
= 3V
V
IN
= 2.4V
V
IN
= 1.2V
0.1
1
10
LOAD (mA)
100
0.01
1000
20
0.01
0.01
1000
0
0.01
0.1
1
10
LOAD (mA)
V
IN
= 3.6V 0.1
V
IN
= 2.4V
V
IN
= 1.2V
0.01
100
1000
3525 G05
3525 G24
3525 G04
LTC3525-3.3 Load Regulation
2.5
2.0
1.5
CHANGE IN V
OUT
(%)
CHANGE IN V
OUT
(%)
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
0
10
20
30 40 50
LOAD (mA)
60
70
80
C
OUT
= 10µF
C
OUT
= 22µF
V
IN
= 1.2V
2.5
2.0
1.5
LTC3525-3.3 Load Regulation
V
IN
= 2.4V
2.5
2.0
1.5
CHANGE IN V
OUT
(%)
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
0
20
40
60
80 100 120 140 160 180
LOAD (mA)
3525 G07
LTC3525-5 Load Regulation
V
IN
= 1.2V
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
C
OUT
= 22µF
C
OUT
= 10µF
C
OUT
= 22µF
C
OUT
= 10µF
–2.5
0
10
20
30
40
LOAD (mA)
50
60
3525 G08
3525 G06
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LTC3525-3/
LTC3525-3.3/LTC3525-5
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C unless otherwise noted.
LTC3525-5 Load Regulation
2.5
2.0
1.5
CHANGE IN V
OUT
(%)
CHANGE IN V
OUT
(%)
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
0
20
40
60
80 100
LOAD (mA)
120
140
C
OUT
= 10µF
C
OUT
= 22µF
V
IN
= 2.4V
2.5
2.0
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
0
50
100
LOAD (mA)
150
200
3525 G10
LTC3525-5 Load Regulation
V
IN
= 3.6V
1200
1100
1000
FREQUENCY (kHz)
900
800
700
600
500
400
Switching Frequency vs V
IN
L = 10µH
LTC3525-5
C
OUT
= 22µF
C
OUT
= 10µF
LTC3525-3.3
300
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
3525 G09
3525 G11
Light Load Burst Frequency
vs Load
40
35
BURST FREQUENCY (kHz)
CHANGE IN V
OUT
(%)
30
25
20
15
10
5
0
0.1
1
LOAD (mA)
C
OUT
= 10µF
0.4
0.3
V
OUT
Variation vs Temperature
(Normalized to 25°C)
120
100
SWITCHING DELAY (µs)
80
60
40
20
0
Startup Delay Coming Out of
Shutdown
0.2
0.1
0
–0.1
–0.2
–0.3
C
OUT
= 22µF
10
3525 G12
–0.4
–40–30–20–10 0 10 20 30 40 50 60 70 80
TEMPERATURE (°C)
3525 G13
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
3525 G14
LTC3525-3.3 Input Current and
V
OUT
at Start-Up
V
IN
= 1.2V
I
OUT
5mA
I
OUT
40mA
I
OUT
80mA
500µs/DIV
3525 G15
LTC3525-3.3 Output Voltage
Ripple
V
OUT
1V/DIV
INPUT
CURRENT
100mA/DIV
50mV/DIV
V
IN
= 1.2V
C
OUT
= 10µF
50µs/DIV
3525 G16
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