LTC3529
1.5A, 1.5MHz Step-Up
DC/DC Converter in
2mm
×
3mm DFN
FEATURES
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DESCRIPTION
The LTC
®
3529 is a 5V output, synchronous, fixed frequency
step-up DC/DC converter optimized for USB On-The-Go
(OTG) hosting applications. This compact USB OTG 5V
V
BUS
converter features a 1.5MHz switching frequency,
internal compensation and a tiny 2mm
×
3mm DFN pack-
age. The LTC3529 can operate from input voltages as low
as 1.8V.
USB OTG-specific features include a fault flag with 22ms
deglitching to indicate when the bus is overloaded, output
disconnect and short-circuit protection. Following a fault,
the LTC3529 can be programmed to either latchoff or
restart after a time-out duration.
Additional features include a <1μA shutdown mode,
soft-start, inrush current limiting and thermal overload
protection. Anti-ring circuitry reduces EMI during low
power operation. The LTC3529 is offered in an 8-lead
2mm
×
3mm
×
0.75mm DFN package.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents including
6404251, 6166527.
Compact Solution for 5V USB On-The-Go
V
BUS
Power
5V at 500mA from Single Li-Ion Cell
Automatic Fault Detection
High Efficiency: Up to 95%
V
IN
Range: 1.8V to 5.25V
Fixed 5V Output
Short-Circuit Protection
1.5MHz Low Noise, Fixed Frequency PWM
Inrush Current Limiting and Internal Soft-Start
Output Disconnect
<1μA Quiescent Current in Shutdown
V
IN
> V
OUT
Operation
8-Lead, 2mm
×
3mm DFN Package
APPLICATIONS
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Personal Media Players
Digital Video Cameras
Digital Multimedia Broadcast Tuners
Digital Cameras
Smart Phones
TYPICAL APPLICATION
Li-Ion Battery to 5V Synchronous Boost Converter
4.7μH
2.5V
TO
4.2V
100
90
Efficiency vs Load Current
0.9
0.8
EFFICIENCY
0.7
POWER LOSS (W)
0.6
0.5
0.4
0.3
0.2
POWER LOSS
1
10
100
LOAD CURRENT (mA)
0.1
0
1000
3529 TA01b
+
Li-Ion
3.3μF
V
IN
370Ω
80
LTC3529
EFFICIENCY (%)
SW
70
60
50
40
30
20
10
0
FAULT
SNSGND
AUTO-RESTART OFF ON
RST
V
OUT
C
OUT
10μF
OFF ON
SHDN
PGND
3529 TA01a
V
OUT
5V
500mA
V
IN
= 3.6V
INDUCTOR = 4.7μH,
COOPER BUSSMANN SD25-4R7
3529fa
1
LTC3529
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
V
OUT
1
SW 2
SHDN
3
PGND 4
9
8 V
IN
7 RST
6 SNSGND
5
FAULT
V
IN
, V
OUT
Voltage ............................................–0.3 to 6V
SHDN,
RST,
FAULT
Voltage..............................–0.3 to 6V
SW Voltage
DC...............................................................–0.3 to 6V
Pulsed <100ns ............................................ –1V to 7V
Operating Temperature Range (Note 2).... –40°C to 85°C
Maximum Junction Temperature (Note 3)............. 125°C
Storage Temperature Range................... –65°C to 125°C
DCB PACKAGE
8-LEAD (2mm 3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 64°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3529EDCB#PBF
TAPE AND REEL
LTC3529EDCB#TRPBF
PART MARKING
LCTZ
PACKAGE DESCRIPTION
8-Lead (2mm
×
3mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 85°C
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/
ELECTRICAL CHARACTERISTICS
PARAMETER
Input Voltage Range
Output Voltage
Quiescent Current - Shutdown
NMOS Switch Leakage Current
PMOS Switch Leakage Current
NMOS Switch On Resistance
PMOS Switch On Resistance
NMOS Current Limit
Current Limit Delay Time to Output
Maximum Duty Cycle
Minimum Duty Cycle
Switching Frequency
SHDN,
RST Input High Voltage
SHDN,
RST Input Low Voltage
SHDN,
RST Input Current
Soft-Start Time
Line Regulation
(Note 4)
(Note 5)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, V
OUT
= 5V unless otherwise noted.
CONDITIONS
l
MIN
1.8
4.85
TYP
5
0.01
0.3
0.3
0.09
0.12
MAX
5.25
5.15
1
15
15
UNITS
V
V
μA
μA
μA
Ω
Ω
A
ns
%
V
SHDN
= 0V, V
OUT
= 0V
V
SW
= 5V
V
SW
= 0V, V
OUT
= 5V
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1.5
40
80
1.2
1
0.35
0.01
2
0.03
1
87
0
1.5
1.8
V
OUT
= 4.5V
V
OUT
= 5.5V
%
MHz
V
V
μA
ms
%/V
V
SHDN
, V
BURST
, V
RST
= 5.5V
V
IN
= 1.8V to 5.25V
3529fa
2
LTC3529
ELECTRICAL CHARACTERISTICS
PARAMETER
FAULT
Delay Time
FAULT
Output Low Voltage
FAULT
Leakage Current
I
FAULT
= 5mA
V
FAULT
= 5.5V
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, V
OUT
= 5V unless otherwise noted.
CONDITIONS
MIN
12
TYP
22
60
10
MAX
35
UNITS
ms
mV
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 LTC3529 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:
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 4:
Current measurements are performed when the LTC3529 is not
switching. The current limit values in operation will be somewhat higher
due to the propagation delay of the comparators.
Note 5:
Specification is guaranteed by design and not 100% tested in
production.
TYPICAL PERFORMANCE CHARACTERISTICS
2 Alkaline Cells to 5V Efficiency
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
1
10
100
LOAD CURRENT (mA)
POWER LOSS
V
IN
= 3V
0
1000
3529 G01
Li-Ion Battery to 5V Efficiency
100
0.7
0.6
POWER LOSS (W)
EFFICIENCY (%)
0.5
0.4
0.3
90
80
70
60
50
40
30
20
0.1
10
0
1
10
100
LOAD CURRENT (mA)
POWER LOSS
0.3
0.2
0.1
0
1000
3529 G02
V
IN
= 3V
EFFICIENCY
V
IN
= 1.8V
V
IN
= 4.1V
V
IN
= 3.6V
V
IN
= 3V
EFFICIENCY
0.7
0.6
0.5
0.4
POWER LOSS (W)
V
IN
= 1.8V
0.2
C
OUT
= 10μF
INDUCTOR = 4.7μH,
COOPER BUSSMANN SD25-4R7
C
OUT
= 10μF
INDUCTOR = 4.7μH,
COOPER BUSSMANN SD25-4R7
Soft-Start Waveforms
V
OUT
5V/DIV
I
L
200mA/DIV
SHDN
5V/DIV
2ms/DIV
V
IN
= 3.6V
V
OUT
= 5V
C
OUT
= 10μF
L = 2.2μH
3529 G03
Load Transient Response
V
OUT
Ripple
V
OUT
200mV/DIV
V
OUT
5mV/DIV
200μs/DIV
V
IN
= 3.6V
V
OUT
= 5V
C
OUT
= 10μF
L = 2.2μH
3529 G04
I
L
500mA/DIV
1μs/DIV
V
IN
= 3.6V
C
OUT
= 10μF
L = 4.7μH
I
LOAD
= 200mA
3529 G05
3529fa
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LTC3529
TYPICAL PERFORMANCE CHARACTERISTICS
Current Limit vs Temperature
1.90
1.85
CHANGE FROM 25°C (%)
1.80
CURRENT LIMIT (A)
1.75
1.70
1.65
1.60
1.55
1.50
1.45
1.40
–45 –25 –5
15 35 55 75
TEMPERATURE (°C)
95 115
3529 G06
Output Voltage Change
vs Temperature
1.0
0.8
0.6
0.4
I
OUT
(mA)
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–50
0
50
100
TEMPERATURE (°C)
150
3529 G07
Maximum Output Current vs V
IN
1600
1400
1200
1000
800
600
400
200
0
1.5
2.0
2.5
3.0 3.5
V
IN
(V)
4.0
4.5
5.0
L = 4.7μH
3529 G08
SW Pin Anti-Ringing
10
I
L
25mA/DIV
NORMALIZED TO 25°C (%)
8
Switching Frequency Variation
vs Temperature
18
16
QUIESCENT CURRENT (mA)
14
12
10
8
6
4
2
90
110
No-Load Input Current vs V
IN
6
4
2
0
–2
–4
–6
–8
SW
2V/DIV
1μs/DIV
V
IN
= 3.6V
C
OUT
= 10μF
L = 4.7μH
3529 G09
–10
–50 –30 –10 10 30 50 70
TEMPERATURE (°C)
0
1.5
2.5
3.5
V
IN
(V)
4.5
5.5
3529 G11
3529 G10
R
DS(ON)
vs Temperature
160
140
120
100
NMOS
80
60
40
20
0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
V
OUT
CHANGE (%)
R
DS(ON)
(mΩ)
PMOS
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
Load Regulation
V
IN
= 3.3V
L = 4.7μH
0
100
200
300
I
LOAD
(mA)
400
500
3529 G13
3529 G12
3529fa
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LTC3529
PIN FUNCTIONS
V
OUT
(Pin 1):
Converter Output, Voltage Sense Input
and Drain of the Internal Synchronous Rectifier MOSFET.
Driver bias is derived from V
OUT
. PCB trace length from
V
OUT
to the output filter capacitor(s) should be as short
and wide as possible.
SW (Pin 2):
Switch Node. This node connects to one
side of the inductor. Keep PCB traces as short and wide
as possible to reduce EMI and voltage overshoot. If the
inductor current falls to zero, or
SHDN
is low, an internal
100Ω anti-ringing switch is connected between SW and
V
IN
to minimize EMI.
SHDN
(Pin 3):
Active-Low Shutdown Input. Forcing this
pin above 1V enables the converter. Forcing this pin below
0.35V disables the converter. Do not float this pin.
PGND (Pin 4):
High Current Ground Connection. The PCB
trace connecting this pin to ground should be as short and
as wide as possible.
FAULT
(Pin 5):
Open-Drain Fault Indicator Output. Pulls
low when an overcurrent condition exists for more than
22ms.
SNSGND (Pin 6):
This pin must be connected to
ground.
RST (Pin 7):
Logic Input to Select Automatic Restart or
Latchoff Following a Fault Shutdown.
• RST = High: Auto-reset mode. In this mode, the LTC3529
will automatically attempt to restart 22ms (typically)
after a fault shutdown.
• RST = Low: Latchoff mode. In this mode, the LTC3529
will latch off for a fault shutdown. The IC will not restart
until the
SHDN
pin is toggled or the supply voltage is
cycled.
V
IN
(Pin 8):
Input Supply Pin.
Exposed Pad (Pin 9):
Small Signal Ground. This is the
ground reference for the internal circuitry of the LTC3529
and must be connected directly to ground.
3529fa
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