LTC3525D-3.3
400mA Micropower
Synchronous Step-Up DC/DC
Converter with Pass Through Mode
FEATURES
■
■
■
■
■
DESCRIPTIO
■
■
■
■
■
■
■
■
V
OUT
Connected to V
IN
in Shutdown
Up to 95% Efficiency
0.85V Minimum Input Start-Up Voltage
Fixed Output Voltage of 3.3V
Delivers 60mA at 3.3V from a 1V Input,
or 140mA at 3.3V from a 1.8V Input
Burst Mode
®
Operation: I
Q
= 7µA
V
IN
Range: 0.5V to 4.5V
Only Three External Components
V
IN
> V
OUT
Operation
Antiringing Control
Short-Circuit and Overtemperature Protection
Very Low Profile of 1mm
Tiny 6-Pin SC70 Package
The LTC
®
3525D-3.3 is a high efficiency synchronous step-
up DC/DC converter that can start up with an input as low
as 0.85V. It offers 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 LTC3525D features a fixed output voltage
of 3.3V. In shutdown, V
OUT
is connected to V
IN
through
the inductor.
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 anti-ringing control and thermal
shutdown. The LTC3525D 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
■
■
■
■
MP3 Players
Portable Instruments
Glucose Meters
Digital Cameras
TYPICAL APPLICATIO
LTC3525D-3.3 Efficiency and
Power Loss vs Load Current
L1*
10µH
100
90
LTC3525D-3.3
V
IN
1.8V to 3.2V
PASS THROUGH ON
SHDN
GND
1µF
V
OUT
GND
10µF
V
IN
SW
V
OUT
3.3V
140mA
80
EFFICIENCY (%)
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
3525d33f
1
LTC3525D-3.3
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
⎯
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
LTC3525DESC6-3.3
SC6 PART MARKING
LCQZ
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
●
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.
PARAMETER
Input Start-Up Voltage
Output Voltage
Quiescent Current, V
OUT
Quiescent Current, V
IN
Quiescent Current, V
IN
- Shutdown
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
= V
IN
= 3.3V
Including Switch Leakage
(Note 3)
(Note 3)
0.4
0.4
●
CONDITIONS
MIN
3.20
TYP
0.85
3.30
7
0.5
3
0.5
0.8
0.45
0.6
0.01
MAX
1
3.40
15
3
10
UNITS
V
V
µA
µA
µA
Ω
Ω
A
1
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 LTC3525DE 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 LTC3525D 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.
3525d33f
2
U
V
µA
W
U
U
W W
W
LTC3525D-3.3
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)
I
IN
(µA)
150
150
100
50
0
0.5
50
250
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
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
= 3V
V
IN
= 2.4V
V
IN
= 1.2V
100
0.1
1
10
POWER LOSS (mW)
100
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
CHANGE IN V
OUT
(%)
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)
U W
4.0
3525 G01
3525 G04
Maximum Startup Load vs V
IN
(Resistive Load)
50
45
200
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
100
0
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
3525 G03
Load Regulation
2.5
2.0
1.5
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
Load Regulation
V
IN
= 2.4V
C
OUT
= 22µF
C
OUT
= 10µF
0.01
1000
0
20
40
60
80 100 120 140 160 180
LOAD (mA)
3525 G07
3525 G06
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
Start-Up 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
3525d33f
3
LTC3525D-3.3
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 G16
V
IN
= 1.2V
C
OUT
= 10µF
Output Voltage Ripple
I
OUT
=
5mA
I
OUT
=
100mA
I
OUT
=
190mA
50mV/DIV
V
IN
= 2.4V
C
OUT
= 22µF
50µs/DIV
4
U W
Output Voltage Ripple
I
OUT
=
5mA
50mV/DIV
I
OUT
=
40mA
I
OUT
=
80mA
50µs/DIV
3525 G17
50mV/DIV
V
IN
= 1.2V
C
OUT
= 22µF
50mA Load Step Response
OUTPUT
RIPPLE
50mV/DIV
LOAD
CURRENT
20mA/DIV
3525 G18
V
IN
= 1.2V
C
OUT
= 22µF
500µs/DIV
3525 G21
100mA Load Step Response
OUTPUT
RIPPLE
50mV/DIV
LOAD
CURRENT
50mA/DIV
500µs/DIV
3525 G22
V
IN
= 2.4V
C
OUT
= 22µF
3525d33f
LTC3525D-3.3
PI FU CTIO S
⎯
S
⎯
H
⎯
D
⎯
N (Pin 1):
Logic Controlled Shutdown Input. Connect
to a voltage >1V to enable the LTC3525D. Connect to a
voltage <0.4V to disable the LTC3525D and connect V
IN
to V
OUT
through the inductor.
GND (Pins 2, 5):
Ground.
V
IN
(Pin 3):
Input Voltage. The LTC3525D is powered from
V
IN
until V
OUT
exceeds V
IN
. Once V
OUT
is greater than (V
IN
+ 0.2V typical), it is powered from V
OUT
. Place a ceramic
bypass capacitor from V
IN
to GND. A minimum value of
1µF is recommended.
V
OUT
(Pin 4):
Output Voltage Sense and the Output of the
Synchronous Rectifier. Connect the output filter capacitor
from V
OUT
to GND, close to the IC. A minimum value of
10µF ceramic is recommended. Use 22µF for reduced
output ripple. The pass-through mode feature connects
V
OUT
to V
IN
through the inductor when
⎯
S
⎯
H
⎯
D
⎯
N is <0.4V.
SW (Pin 6):
Switch Pin. Connect an inductor from this
pin to V
IN
. An internal antiringing resistor is connected
across SW and V
IN
after the inductor current has dropped
to zero to minimize EMI.
BLOCK DIAGRA
V
OUT
V
SEL
V
BEST
VB
4
V
OUT
SHUTDOWN
SHUTDOWN
GATE DRIVERS
AND
ANTI-CROSS
CONDUCTION
OFFSET
V
REF
UVLO
V
REF
UVLO
–
I
PK
WELL
SWITCH
SHDN
1
I
PK
COMPARATOR
STARTUP
LOGIC
–
I
VAL
SHUTDOWN
TSD
WAKE
+
INTEGRATOR
ADJUST
5
GND
2
GND
SLEEP
COMPARATOR
+
THERMAL
SHUTDOWN
–
+
W
U
U
U
SW
6
V
IN
3
+
–
ADJUST
+
OFFSET
–
ADJUST
I
VALLEY
COMPARATOR
FB
V
REF
3525 BD
3525d33f
5
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
