LTC3525-3/
LTC3525-3.3/LTC3525-5
400mA Micropower
Synchronous Step-Up DC/DC
Converter with Output Disconnect
FEATURES
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DESCRIPTIO
■
■
■
■
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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
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Patents Pending
APPLICATIO S
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MP3 Players
Portable Instruments
Glucose Meters
Digital Cameras
TYPICAL APPLICATIO
LTC3525-3.3 Efficiency and Power
Loss vs Load Current
L1*
10µH
100
90
LTC3525-3.3
V
IN
1V to 1.6V
OFF ON
SHDN
GND
1µF
V
OUT
GND
10µF
V
IN
SW
V
OUT
3.3V
60mA
EFFICIENCY (%)
80
EFFICIENCY
70
60
POWER LOSS
50
40
3525 TA01
30
20
0.01
0.1
1
10
LOAD (mA)
*MURATA LQH32CN100K53
U
100
10
POWER LOSS (mW)
1
0.1
V
IN
= 3V
V
IN
= 2.4V
V
IN
= 1.2V
100
0.01
1000
LT3525 • TA02
U
U
3525fa
1
LTC3525-3/
LTC3525-3.3/LTC3525-5
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
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
⎯
S
⎯
H
⎯
D
⎯
N 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 PART NUMBER
LTC3525ESC6-3
LTC3525ESC6-3.3
LTC3525ESC6-5
SC6 PART MARKING
LCDR
LBTG
LBWT
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
PARAMETER
Input Start-Up Voltage
Output Voltage
Quiescent Current, V
OUT
Quiescent Current, V
IN
Quiescent Current, V
IN
- Shutdown
NMOS Switch Leakage
PMOS Switch Leakage
NMOS Switch On Resistance
PMOS Switch On Resistance
Peak Current Limit
⎯
SH
⎯
D
⎯
N Threshold
⎯
⎯
SH
⎯
D
⎯
N Input Current
⎯
(Note 6)
(LTC3525-3)
The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 1.2V, V
⎯
S
⎯
H
⎯
D
⎯
N
= 1.2V, V
OUT
= 3V unless otherwise noted.
CONDITIONS
●
MIN
2.91
TYP
0.85
3.00
7
0.5
0.1
0.1
0.1
0.6
0.9
MAX
1
3.09
15
3
1
1
3
UNITS
V
V
µA
µA
µA
µA
µA
Ω
Ω
A
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
(Note 4)
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
(Note 4)
⎯
S
⎯
H
⎯
D
⎯
N = 0V, V
OUT
= 0V
Not Including Switch Leakage
V
IN
= V
OUT
= V
SW
= 5V,
⎯
S
⎯
H
⎯
D
⎯
N = 0V
V
IN
= V
SW
= 5V, V
OUT
= 0V,
⎯
S
⎯
H
⎯
D
⎯
N = 0V
(Note 3)
(Note 3)
0.4
0.4
V
⎯
S
⎯
H
⎯
D
⎯
N
= V
IN
or V
OUT
0.45
0.6
0.01
1
1
3525fa
2
U
V
µA
W
U
U
W W
W
LTC3525-3/
LTC3525-3.3/LTC3525-5
ELECTRICAL CHARACTERISTICS
PARAMETER
Input Start-Up Voltage
Output Voltage
Quiescent Current, V
OUT
Quiescent Current, V
IN
Quiescent Current, V
IN
- Shutdown
NMOS Switch Leakage
PMOS Switch Leakage
NMOS Switch On Resistance
PMOS Switch On Resistance
Peak Current Limit
⎯
S
⎯
H
⎯
D
⎯
N Threshold
⎯
SH
⎯
D
⎯
N Input Current
⎯
V
⎯
S
⎯
H
⎯
D
⎯
N
= V
IN
or V
OUT
(Note 6)
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
(Note 4)
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
(Note 4)
⎯
S
⎯
H
⎯
D
⎯
N = 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,
⎯
S
⎯
H
⎯
D
⎯
N = 0V
(Note 3)
(Note 3)
0.4
0.4
●
(LTC3525-3.3)
The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 1.2V, V
⎯
S
⎯
H
⎯
D
⎯
N
= 1.2V, V
OUT
= 3.3V unless otherwise noted.
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
1
1
MAX
1
3.40
15
3
1
1
3
UNITS
V
V
µA
µA
µA
µA
µA
Ω
Ω
A
V
µA
(LTC3525-5)
The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 2.4V, V
⎯
S
⎯
H
⎯
D
⎯
N
= 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
PMOS Switch Leakage
NMOS Switch On Resistance
PMOS Switch On Resistance
Peak Current Limit
⎯
SH
⎯
D
⎯
N Threshold
⎯
⎯
SH
⎯
D
⎯
N Input Current
⎯
V
⎯
S
⎯
H
⎯
D
⎯
N
= V
IN
or V
OUT
(Note 6)
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
(Note 4)
⎯
S
⎯
H
⎯
D
⎯
N = V
IN
(Note 4)
⎯
S
⎯
H
⎯
D
⎯
N = 0V, V
OUT
= 0V
Not Including Switch Leakage
V
IN
= V
OUT
= V
SW
= 5V,
⎯
S
⎯
H
⎯
D
⎯
N = 0V
V
IN
= V
SW
= 5V, V
OUT
= 0V,
⎯
S
⎯
H
⎯
D
⎯
N = 0V
(Note 3)
(Note 3)
0.4
0.4
●
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.
3525fa
3
LTC3525-3/
LTC3525-3.3/LTC3525-5
TYPICAL PERFOR A CE CHARACTERISTICS
T
A
= 25°C unless otherwise noted.
Maximum Output Current vs V
IN
(for V
OUT
to Drop 2.5%)
300
250
200
I
OUT
(mA)
150
100
50
0
0.5
50
LTC3525-3
LTC3525-3.3
I
IN
(µA)
LTC3525-5
LOAD (mA)
150
LTC3525-3.3
250
LTC3525-5
200
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
LTC3525-3 Efficiency and Power
Loss vs Load
100
90
80
EFFICIENCY (%)
EFFICIENCY
70
60
POWER LOSS
50
40
30
20
0.01
0.1
1
10
LOAD (mA)
V
IN
= 2.4V
V
IN
= 1.2V
100
0.1
1
10
POWER LOSS (mW)
EFFICIENCY (%)
100
100
90
80
70
60
POWER LOSS
50
40
30
20
0.01
0.1
1
10
LOAD (mA)
V
IN
= 3V
V
IN
= 2.4V
V
IN
= 1.2V
100
0.1
1
EFFICIENCY (%)
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
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
CHANGE IN V
OUT
(%)
4
U W
4.0
3525 G01
3525 G24
Maximum Startup Load vs V
IN
(Resistive Load)
50
45
40
35
30
25
20
15
10
5
0
4.5
0.5
1.0
1.5
2.0
V
IN
(V)
2.5
3.0
3525 G02
No-Load Input Current vs V
IN
LTC3525-5
100
LTC3525-3
LTC3525-3.3
0
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
3525 G03
LTC3525-3.3 Efficiency and Power
Loss vs Load
100
100
90
10
POWER LOSS (mW)
EFFICIENCY
80
70
60
50
40
30
20
10
LTC3525-5 Efficiency and Power
Loss vs Load
1000
100
EFFICIENCY
10
POWER LOSS
POWER LOSS (mW)
1
0.01
1000
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 G04
LTC3525-3.3 Load Regulation
V
IN
= 2.4V
2.5
2.0
1.5
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
C
OUT
= 22µF
C
OUT
= 22µF
C
OUT
= 10µF
C
OUT
= 10µF
–2.5
0
10
20
30
40
LOAD (mA)
50
60
3525 G08
3525 G06
3525fa
LTC3525-3/
LTC3525-3.3/LTC3525-5
TYPICAL PERFOR A CE 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
FREQUENCY (kHz)
Light Load Burst Frequency
vs Load
40
35
BURST FREQUENCY (kHz)
CHANGE IN V
OUT
(%)
30
25
20
C
OUT
= 10µF
15
10
C
OUT
= 22µF
5
0
0.1
1
LOAD (mA)
10
3525 G12
SWITCHING DELAY (µs)
LTC3525-3.3 Input Current and
V
OUT
at Startup
V
IN
= 1.2V
I
OUT
=
5mA
V
OUT
1V/DIV
INPUT
CURRENT
100mA/DIV
500µs/DIV
3525 G15
U W
3525 G09
LTC3525-5 Load Regulation
V
IN
= 3.6V
1200
1100
Switching Frequency vs V
IN
L = 10µH
LTC3525-5
1000
900
800
700
600
500
400
300
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
LTC3525-3.3
C
OUT
= 22µF
C
OUT
= 10µF
3525 G11
V
OUT
Variation vs Temperature
(Normalized to 25°C)
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–40–30–20–10 0 10 20 30 40 50 60 70 80
TEMPERATURE (°C)
3525 G13
Startup Delay Coming Out of
Shutdown
120
100
80
60
40
20
0
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
3525 G14
LTC3525-3.3 Output Voltage
Ripple
I
OUT
=
40mA
I
OUT
=
80mA
50µs/DIV
3525 G16
50mV/DIV
V
IN
= 1.2V
C
OUT
= 10µF
3525fa
5
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