LTC3525L-3
400mA Micropower
Synchronous Step-Up DC/DC
Converter with Output Disconnect
FEATURES
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DESCRIPTIO
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Startup at 0.7V Typical, 0.88V Guaranteed
Up to 95% Efficiency
Output Disconnect and Inrush Current Limit
3V Fixed Output Voltage
Delivers 65mA at 3V from a 1V Input or 160mA
from a 1.8V input
Burst Mode
®
Operation: I
Q
= 7µA
V
IN
: 0.5V to 4.5V
Only Three External Components
V
IN
> V
OUT
Operation
<1µA Shutdown Current
Antiringing Control
Short-Circuit and Overtemperature Protection
Tiny 6-Pin SC70 Package
The LTC
®
3525L-3 is a high efficiency synchronous step-
up DC/DC converter with output disconnect that can
start up with an input as low as 0.7V. It offers a compact,
high efficiency alternative to charge pumps in single
cell or dual cell alkaline applications. Only three small
external components are required. The LTC3525L-3
generates a fixed 3V output voltage.
The device includes a 0.5 N-channel MOSFET switch
and a 0.85 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 LTC3525L-3
is available in a tiny 6-pin SC70 package.
, LT, LTC and LTM 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
LTC3525L-3 Efficiency and Power
Loss vs Load Current
L1*
10µH
100
90
LTC3525L-3
V
IN
0.9V to 1.6V
OFF ON
SHDN
GND
1µF
V
OUT
GND
10µF
V
IN
SW
V
OUT
3V
65mA
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
= 2.4V
V
IN
= 1.2V
100
0.01
1000
LT3525 • TA02
U
U
3525lf
1
LTC3525L-3
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
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
JA
= 256°C/W IN FREE AIR,
JA
= 150°C/W ON BOARD
OVER GROUND PLANE
ORDER PART NUMBER
LTC3525LESC6-3
SC6 PART MARKING
LCPY
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
Minimum 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
SHDN Threshold
SHDN Input Current
(Note 6)
(LTC3525L-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
SHDN
= 1.2V, V
OUT
= 3V unless otherwise noted.
CONDITIONS
●
MIN
2.91
TYP
0.7
3.00
7
0.5
0.1
0.1
0.1
0.5
0.85
MAX
0.88
3.09
15
3
1
3
6
UNITS
V
V
µA
µA
µA
µA
µA
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
0.3
V
SHDN
= V
IN
or V
OUT
0.45
0.5
0.01
0.88
1
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 LTC3525LE-3 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 LTC3525L-3 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.
3525lf
2
U
A
V
µA
W
U
U
W W
W
LTC3525L-3
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
LOAD (mA)
I
OUT
(mA)
150
100
50
0
0.5
30
25
20
15
10
5
0
0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00
V
IN
(V)
3525 G02
I
IN
(µA)
1.0
1.5
V
IN
(V)
2.0
Efficiency and Power Loss
vs Load
100
90
100
CHANGE IN V
OUT
(%)
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
U W
3525 G01
Maximum Startup Load vs V
IN
(Resistive Load)
30
25
20
LTC3525L-3
15
10
5
0
No-Load Input Current vs V
IN
2.5
1.0
1.5
2.0
V
IN
(V)
2.5
3.0
3525 G03
Load Regulation
2.5
2.0
1.5
10
POWER LOSS (mW)
V
IN
= 1.2V
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
1
0.1
0.01
1000
3525 G24
3525 G06
3525lf
3
LTC3525L-3
TYPICAL PERFOR A CE CHARACTERISTICS
T
A
= 25°C unless otherwise noted.
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)
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
4
U W
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
Output Voltage Ripple
I
OUT
=
40mA
I
OUT
=
80mA
50µs/DIV
3525 G16
50mV/DIV
V
IN
= 1.2V
C
OUT
= 10µF
3525lf
LTC3525L-3
TYPICAL PERFOR A CE CHARACTERISTICS
T
A
= 25°C unless otherwise noted.
Output Voltage Ripple
I
OUT
=
5mA
I
OUT
=
40mA
I
OUT
=
80mA
50µs/DIV
3525 G17
V
IN
= 1.2V
C
OUT
= 22µF
50mA Load Step Response
OUTPUT
RIPPLE
50mV/DIV
LOAD
CURRENT
20mA/DIV
500µs/DIV
3525 G21
V
IN
= 1.2V
C
OUT
= 22µF
U W
Output Voltage Ripple
I
OUT
=
5mA
50mV/DIV
I
OUT
=
100mA
I
OUT
=
190mA
50mV/DIV
V
IN
= 2.4V
C
OUT
= 22µF
50µs/DIV
3525 G18
100mA Load Step Response
OUTPUT
RIPPLE
50mV/DIV
LOAD
CURRENT
50mA/DIV
500µs/DIV
3525 G22
V
IN
= 2.4V
C
OUT
= 22µF
3525lf
5
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