FEATURES
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LTC3526L
550mA 1MHz Synchronous
Step-Up DC/DC Converters
in 2mm
×
2mm DFN
DESCRIPTIO
The LTC
®
3526L is a synchronous, fixed frequency step-up
DC/DC converter with output disconnect. Synchronous
rectification enables high efficiency in the low profile 2mm
×
2mm DFN package. Battery life in single AA/AAA powered
products is extended further with a 680mV start-up voltage
and operation down to 500mV once started.
A switching frequency of 1MHz minimizes solution foot-
print by allowing the use of tiny, low profile inductors
and ceramic capacitors. The current mode PWM design
is internally compensated, reducing external parts count.
The LTC3526L features Burst Mode operation at light load
conditions allowing it to maintain high efficiency over a
wide range of load. Anti-ring circuitry reduces EMI by
damping the inductor in discontinuous mode. Additional
features include a low shutdown current of under 1µA and
thermal shutdown.
The LTC3526L is housed in a 2mm
×
2mm
×
0.75mm
DFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6498466, 6611131, 5481178, 6580258, 6304066.
Delivers 3.3V at 100mA from a Single Alkaline/
NiMH Cell or 3.3V at 200mA from Two Cells
V
IN
Start-Up Voltage: 680mV
1.5V to 5.25V V
OUT
Range
Up to 94% Efficiency
Output Disconnect
1MHz Fixed Frequency Operation
V
IN
> V
OUT
Operation
Integrated Soft-Start
Current Mode Control with Internal Compensation
Burst Mode
®
Operation with 9µA Quiescent Current
Internal Synchronous Rectifier
Logic Controlled Shutdown (I
Q
< 1µA)
Anti-Ringing Control
Low Profile (2mm
×
2mm
×
0.75mm)
DFN-6 Package
APPLICATIO S
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Medical Instruments
Flash-Based MP3 Players
Noise Canceling Headphones
Wireless Mice
Bluetooth Headsets
TYPICAL APPLICATIO
4.7µH
Efficiency and Power Loss vs Load Current
100
90
80
V
IN
= 2.4V
EFFICIENCY
100
POWER LOSS (mW)
1000
SW
V
IN
1.6V TO 3.2V
4.7µF
OFF ON
V
IN
V
OUT
1.78M
EFFICIENCY (%)
V
OUT
3.3V
200mA
4.7µF
1M
3526 TA01a
70
60
50
40
30
20
10
0
0.01
0.1
1
10
100
0.01
1000
0.1
POWER LOSS
1
10
LTC3526L
SHDN
GND
FB
U
U
U
LOAD CURRENT (mA)
!# $ 6) >
3526lf
1
LTC3526L
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
SW 1
GND 2
V
IN
3
7
6 V
OUT
5 FB
4 SHDN
V
IN
Voltage ................................................... –0.3V to 6V
SW Voltage
DC............................................................ –0.3V to 6V
Pulsed <100ns ......................................... –0.3V to 7V
⎯
S
⎯
H
⎯
D
⎯
N, FB Voltage ........................................ –0.3V to 6V
V
OUT
............................................................. –0.3V to 6V
Operating Temperature Range
(Notes 2, 5) .............................................. –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
DC PACKAGE
6-LEAD (2mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 60°C/W (NOTE 6)
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PC BOARD
ORDER PART NUMBER
LTC3526LEDC
DC PART MARKING
LCSS
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 Start-Up Input Voltage
Input Voltage Range
Output Voltage Adjust Range
Feedback Pin Voltage
Feedback Pin Input Current
Quiescent Current—Shutdown
Quiescent Current—Active
Quiescent Current—Burst
N-Channel MOSFET Switch Leakage Current
P-Channel MOSFET Switch Leakage Current
N-Channel MOSFET Switch On Resistance
P-Channel MOSFET Switch On Resistance
N-Channel MOSFET Current Limit
Current Limit Delay to Output
Maximum Duty Cycle
Minimum Duty Cycle
Switching Frequency
⎯
SHDN Pin Input High Voltage
⎯ ⎯ ⎯
⎯
SH
⎯
D
⎯
N Pin Input Low Voltage
⎯
(Note 3)
V
FB
= 1.15V
V
FB
= 1.3V
V
FB
= 1.30V
The
●
denotes the specifications which apply over the specified operating
temperature range of –40°C to 85°C, otherwise specifications are at T
A
= 25°C. V
IN
= 1.2V, V
OUT
= 3.3V unless otherwise noted.
CONDITIONS
I
LOAD
= 1mA
After Start-Up. (Minimm Voltage is Load Dependent)
●
●
●
MIN
0.5
1.5
1.165
TYP
0.68
MAX
0.8
5
5.25
UNITS
V
V
V
V
nA
µA
µA
µA
µA
µA
Ω
Ω
mA
ns
%
1.195
1
0.01
250
9
0.1
0.1
0.4
0.6
1.225
50
1
500
18
5
10
V
⎯
S
⎯
H
⎯
D
⎯
N
= 0V, Not Including Switch Leakage, V
OUT
= 0V
Measured on V
OUT
, Nonswitching
Measured on V
OUT
, FB > 1.230V
V
SW
= 5V
V
SW
= 5V, V
OUT
= 0V
V
OUT
= 3.3V
V
OUT
= 3.3V
●
550
87
0.75
0.8
750
60
90
0
1
1.25
0.3
●
●
●
2
U
%
MHz
V
V
3526lf
W
U
U
W W
W
LTC3526L
ELECTRICAL CHARACTERISTICS
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 reli-
ability and lifetime.
Note 2:
The LTC3526LE is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over –40°C to 85°C operating tempera-
ture 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 made when the output 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 result in device degradation or failure.
Note 6:
Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal resistance much higher than
60°C/W.
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency vs Load Current and V
IN
for V
OUT
= 1.8V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
PLOSS AT V
IN
= 1.0V
PLOSS AT V
IN
= 1.2V
PLOSS AT V
IN
= 1.5V
1
10
100
LOAD CURRENT (mA)
0.1
1
V
IN
= 1.0V
V
IN
= 1.2V
V
IN
= 1.5V
100
POWER LOSS (mW)
EFFICIENCY (%)
1000
100
90
80
70
60
50
40
30
20
10
0
0.01
V
IN
= 1.2V
V
IN
= 1.8V
V
IN
= 2.4V
V
IN
= 3.0V
100
POWER LOSS (mW)
I
IN
(
m
A)
Efficiency vs Load Current and V
IN
for V
OUT
= 5V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
10
V
IN
= 1.2V
V
IN
= 2.4V
V
IN
= 3.6V 1
V
IN
= 4.2V
100
300
I
OUT
(mA)
250
200
POWER LOSS (mW)
1000
400
350
V
OUT
= 5V
150
100
50
0
0.5
L = 4.7µH
1.0
1.5
2.0
2.5
V
IN
(V)
!# $ / #
LOAD (Ω)
PLOSS AT V
IN
= 1.2V
0.1
PLOSS AT V
IN
= 2.4V
PLOSS AT V
IN
= 3.6V
PLOSS AT V
IN
= 4.2V
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
!# $ / !
U W
!# $ /
Efficiency vs Load Current and V
IN
for V
OUT
= 3.3V
1000
100
90
80
70
60
50
40
30
20
No-Load Input Current vs V
IN
V
OUT
= 5V
V
OUT
= 3.3V
V
OUT
= 2.5V
V
OUT
= 1.8V
10
10
1
0.01
1000
PLOSS AT V
IN
= 1.2V
0.1
PLOSS AT V
IN
= 1.8V
PLOSS AT V
IN
= 2.4V
PLOSS AT V
IN
= 3.0V
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
!# $ /
10
0.5
1.0
1.5
2.0
2.5
V
IN
(V)
3.0
3.5
4.0
4.5
!# $ / "
Maximum Output Current vs V
IN
V
OUT
= 3.3V
V
OUT
= 2.5V
V
OUT
= 1.8V
1000
10000
Minimum Load Resistance
During Start-Up vs V
IN
V
OUT
= 3.3V
100
3.0
3.5
4.0
4.5
10
0.65
0.75
0.85
0.95
V
IN
(V)
1.05
1.15
3526 G06
3526lf
3
LTC3526L
TYPICAL PERFOR A CE CHARACTERISTICS
Start-Up Delay Time vs V
IN
100
90
80
LOAD CURRENT (mA)
70
DELAY (µs)
60
50
40
30
20
10
0
1.0
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
0
1
1.25
V
IN
(V)
1.5
!# $ / &=
20
LEAVE BURST
15
ENTER BURST
10
5
LOAD CURRENT (mA)
Burst Mode Threshold Current
vs V
IN
50
V
OUT
= 3.3V
45 C
OUT
= 10µF
L = 4.7µH
40
LOAD CURRENT (mA)
35
30
25
20
15
10
5
0
1.0
1.5
2.0
V
IN
(V)
2.5
3.0
3526 G08c
FREQUENCY CHANGE (%)
LOAD CURRENT (mA)
LEAVE BURST
ENTER BURST
R
DS(ON)
vs V
OUT
0.90
0.85
0.80
0.75
0.70
R
DS(ON)
(Ω)
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
1.5
2.0
2.5
3.0 3.5
V
OUT
(V)
4.0
4.5
5.0
NMOS
PMOS
FREQUECNY CHANGE (%)
10
8
6
4
2
0
–2
–4
–6
–8
R
DS(ON)
CHANGE (%)
4
U W
3526 G07
3526 G10
Burst Mode Threshold Current
vs V
IN
30
V
OUT
= 1.8V
C
OUT
= 10µF
25 L = 4.7µH
40
Burst Mode Threshold Current
vs V
IN
V
OUT
= 2.5V
35 C
OUT
= 10µF
L = 4.7µH
30
25
LEAVE BURST
20
15
ENTER BURST
10
5
0
1
1.25
V
IN
(V)
3526 G08b
1.5
1.75
Burst Mode Threshold Current
vs V
IN
60
50
40
LEAVE BURST
30
20
ENTER BURST
10
0
1.0
3
V
OUT
= 5V
C
OUT
= 10µF
L = 4.7µH
2
1
0
–1
–2
Oscillator Frequency Change
vs V
OUT
NORMALIZED TO V
OUT
= 3.3V
1.5
2.0
2.5 3.0
V
IN
(V)
3.5
4.0
4.5
–3
1.5
2.0
2.5
3.0 3.5
V
OUT
(V)
4.0
4.5
5.0
!# $ / &@
3526 G09
Oscillator Frequency Change
vs Temperature
1.3
NORMALIZED TO 25°C
1.2
1.1
1.0
0.9
0.8
R
DS(ON)
Change vs Temperature
NORMALIZED TO 25°C
–10
–50
–30
–10 10
30
50
TEMPERATURE (°C)
70
90
0.7
–50
–30
–10 10
30
50
TEMPERATURE (°C)
70
90
!# $ /
!# $ /
3526lf
LTC3526L
TYPICAL PERFOR A CE CHARACTERISTICS
V
FB
vs Temperature
0.50
0.25
CHANGE IN V
FB
(%)
0
V
IN
(V)
–0.25
–0.50
–0.75
–1.00
–60 –40 –20 0
20 40 60
TEMPERATURE (°C)
0.80
NORMALIZED TO 25°C
0.75
1mA LOAD
0.70
0.65
NO LOAD
0.60
0.55
0.50
–50
I
Q
(µA)
9.0
8.5
8.0
7.5
7.0
1.5
Fixed Frequency Switching
Waveform and V
OUT
Ripple
SW PIN
2V/DIV
V
OUT
10mV/DIV
AC COUPLED
V
IN
= 1.2V
500ns/DIV
V
OUT
= 3.3V AT 100mA
C
OUT
= 10µF
3526 G16
Load Step Response (from Burst
Mode Operation)
V
OUT
100mV/DIV
AC COUPLED
LOAD
CURRENT
50mA/DIV
V
IN
= 3.6V
100µs/DIV
V
OUT
= 5V
20mA TO 170mA STEP
C
OUT
= 10µF
3526 G19
U W
80
3526 G13
Start-Up Voltage vs Temperature
10.0
9.5
Burst Mode Quiesent Current
vs V
OUT
100
25
0
25
50
TEMPERATURE (°C)
75
100
3526 G14
2.0
2.5
3.0 3.5
V
OUT
(V)
4.0
4.5
5.0
3526 G15
Burst Mode Waveforms
SW PIN
2V/DIV
V
OUT
20mV/DIV
AC COUPLED
INDUCTOR
CURRENT
0.2A/DIV
V
IN
= 1.2V
V
OUT
= 3.3V
C
OUT
= 10
m
F
V
OUT
1V/DIV
INPUT
CURRENT
0.2A/DIV
SHDN PIN
1V/DIV
10
m
s/DIV
3526 G17
V
OUT
and I
IN
During Soft-Start
V
OUT
= 3.3V
C
OUT
= 10µF
200µs/DIV
3526 G18
Load Step Response
(Fixed Frequency)
V
OUT
100mV/DIV
AC COUPLED
LOAD
CURRENT
50mA/DIV
V
IN
= 3.6V
100µs/DIV
V
OUT
= 5V
50mA TO 150mA STEP
C
OUT
= 10µF
3526 G20
3526lf
5
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