FEATURES
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LTC3534
7V, 500mA Synchronous
Buck-Boost DC/DC
Converter
DESCRIPTION
The LTC
®
3534 is a wide V
IN
range, highly efficient, fixed
frequency, buck-boost DC/DC converter that operates
from input voltages above, below or equal to the output
voltage. The topology incorporated in the IC provides a
continuous transfer function through all operating modes,
making the product ideal for multi-cell Alkaline/NiMH or
single Lithium-Ion/Polymer applications where the output
voltage is within the battery voltage range.
The LTC3534 offers extended V
IN
and V
OUT
ranges of 2.4V
to 7V and 1.8V to 7V, respectively. Quiescent current is
only 25μA in Burst Mode operation, maximizing battery
life in portable applications. Burst Mode operation is user
controlled and can be enabled by driving the PWM pin
low. If the PWM pin is driven high then fixed frequency
switching is enabled.
Other features include fixed 1MHz operating frequency, a
<1μA shutdown, short-circuit protection, programmable
soft-start, current limit and thermal overload protection.
The LTC3534 is available in the thermally enhanced 16-lead
(3mm
×
5mm) DFN and 16-lead GN packages.
L,
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.
Regulated Output with Input Voltages Above,
Below or Equal to the Output
2.4V to 7V Input and 1.8V to 7V Output
Voltage Range
5V V
OUT
at 500mA from 4 AA Cells
Single Inductor
Synchronous Rectification: Up to 94% Efficiency
Burst Mode
®
Operation with 25μA I
Q
Output Disconnect in Shutdown
1MHz Switching Frequency
<1μA Shutdown Current
Small Thermally Enhanced 16-Lead (5mm
×
3mm
×
0.75mm) DFN and 16-Lead GN Packages
APPLICATIONS
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Medical Instruments
Portable Barcode Readers
Portable Inventory Terminals
USB to 5V Supply
Handheld GPS
TYPICAL APPLICATION
4 AA Cells to 5V at 500mA Buck-Boost Converter
5μH
100
4 AA Cells to 5V Efficiency vs V
IN
95
SW1
V
IN
3.6V TO 6.4V
4 AA
CELLS
SW2
V
OUT
10k
LTC3534
FB
OFF ON
BURST PWM
RUN/SS
PWM
V
C
162k
3534 TA01a
+
10μF
EFFICIENCY (%)
PV
IN
V
IN
649k
V
OUT
5V
22μF 500mA
PWM I
OUT
= 300mA
90
PWM I
OUT
= 500mA
85
33pF
15k
80
PGND1 GND PGND2 330pF
75
3.6
4.0
4.4
4.8 5.2
V
IN
(V)
5.6
6.0
6.4
3534 TA01b
3534f
1
LTC3534
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
IN
, PV
IN
Voltages ........................................ –0.3V to 8V
V
OUT
Voltage ................................................ –0.3V to 8V
SW1, SW2 Voltages
DC............................................................ –0.3V to 8V
Pulsed < 100ns ........................................ –0.3V to 9V
RUN/SS, PWM Voltages............................... –0.3V to 8V
V
C
, FB Voltages ............................................ –0.3V to 6V
Operating Temperature Range (Note 2).... –40°C to 85°C
Maximum Junction Temperature (Note 3)............. 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature
(Soldering, 10sec; GN Package) ........................... 300°C
PIN CONFIGURATION
TOP VIEW
GND
RUN/SS
GND
PGND1
SW1
SW2
PGND2
GND
1
2
3
4
5
6
7
8
17
16 GND
15 FB
14 V
C
13 V
IN
12 PV
IN
11 V
OUT
10 PWM
9
GND
GND
RUN/SS
GND
PGND1
SW1
SW2
PGND2
GND
1
2
3
4
5
6
7
8
TOP VIEW
16 GND
15 FB
14 V
C
13 V
IN
12 PV
IN
11 V
OUT
10 PWM
9
GND
DHC PACKAGE
16-LEAD (5mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W (4-LAYER BOARD),
θ
JC
= 4°C/W
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
GN PACKAGE
16-LEAD PLASTIC SSOP NARROW - FUSED
T
JMAX
= 125°C,θ
JA
= 90°C/W (4-LAYER BOARD),
θ
JC
= 37°C/W
PINS 1, 8, 9, AND 16 ARE PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3534EDHC#PBF
LTC3534EGN#PBF
LEAD BASED FINISH
LTC3534EDHC
LTC3534EGN
TAPE AND REEL
LTC3534EDHC#TRPBF
LTC3534EGN#TRPBF
TAPE AND REEL
LTC3534EDHC#TR
LTC3534EDE#TR
PART MARKING
3534
3534
PART MARKING
3534
3534
PACKAGE DESCRIPTION
16-Lead (5mm
×
3mm) Plastic DFN
16-Lead SSOP Narrow - Fused
PACKAGE DESCRIPTION
16-Lead (5mm
×
3mm) Plastic DFN
16-Lead SSOP Narrow - Fused
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
3534f
2
LTC3534
ELECTRICAL CHARACTERISTICS
PARAMETER
Input Start-Up Voltage
Input Operating Range
Output Voltage Adjust Range
Feedback Voltage
Feedback Input Current
V
IN
Quiescent Current – Burst Mode
Operation
V
IN
Quiescent Current – Shutdown
V
IN
Quiescent Current – Active
Input Current Limit
Reverse Current Limit
Burst Current Limit
NMOS Switches Leakage
PMOS Switches Leakage
PMOS Switches On-Resistance
NMOS B Switch On-Resistance
NMOS C Switch On-Resistance
Maximum Duty Cycle
Minimum Duty Cycle
Frequency
Error Amp AV
OL
Error Amp Source Current
Error Amp Sink Current
RUN/SS Threshold
RUN/SS Input Current – Shutdown
RUN/SS Input Current – Active
PWM Threshold
PWM Input Current
V
RUN/SS
= 400mV; IC is Shut Down
V
RUN/SS
= 5V; IC is Enabled
Measured at PWM Pin; Voltage at which Burst Mode Operation is
Disabled (PWMing Enabled)
V
PWM
= 5V
0.4
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
OUT
= 5V, unless otherwise noted.
CONDITIONS
l
l
l
MIN
2.4
1.8
0.975
TYP
2.2
MAX
2.4
7
7
UNITS
V
V
V
V
nA
μA
μA
μA
A
mA
mA
(Note 4)
V
FB
= Measured Feedback Voltage (Note 4)
V
FB
= 1.2V, V
PWM
= 0V (Note 5)
V
RUN/SS
= 0V, Not Including Switch Leakage, V
OUT
= 0V
V
FB
= 1.2V, V
PWM
= 5V (Note 5)
V
PWM
= 5V
V
PWM
= 5V
V
PWM
= 0V
Switches B and C
Switches A and D
Switches A and D
Switch B
Switch C
Boost (% Switch C On)
Buck (% Switch A On)
l
1
1
25
0.1
420
1.015
50
50
1
700
l
1
1.8
500
400
0.1
0.1
260
275
215
7
10
μA
μA
mΩ
mΩ
mΩ
%
%
l
l
l
l
75
100
0.80
85
0
1
74
–15
225
1.15
%
MHz
dB
μA
μA
(Note 4)
0.4
1
0.02
0.28
1
1.25
1.4
1
1
1.4
2.5
V
μA
μA
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 LTC3534E 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 result in device degradation or failure.
Note 4:
The IC is tested in a feedback loop to make this measurement.
Note 5:
Current Measurements are performed when the outputs are not
switching.
3534f
3
LTC3534
TYPICAL PERFORMANCE CHARACTERISTICS
4 Alkaline Cells to 5V Efficiency
vs I
LOAD
100
Burst
90 Mode
OPERATION
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0.01
0.1
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 6.4V
1
10
100
LOAD CURRENT (mA)
1000
3534 G01
T
A
= 25°C, unless otherwise noted.
USB to 5V Efficiency vs I
LOAD
100
Burst
90 Mode
OPERATION
80
70
60
50
40
30
20
10
0.01
0.1
V
IN
= 4.35V
V
IN
= 4.8V
V
IN
= 5.25V
1
10
100
LOAD CURRENT (mA)
1000
3534 G02
EFFICIENCY (%)
Active Quiescent and Burst Mode
SLEEP Currents vs V
IN
425
ACTIVE QUIESCENT CURRENT (μA)
V
FB
= 1.2V
ACTIVE QUIESCENT CURRENT
415
28
30
Burst Mode SLEEP CURRENT (μA)
3.3
3.0
CURRENT LIMIT (A)
2.7
2.4
2.1
Current Limits vs V
IN
V
OUT
= 5V
PEAK CURRENT LIMIT
405
26
395
Burst Mode SLEEP CURRENT
24
LINEAR CURRENT LIMIT
1.8
1.5
2.4
385
2.4
3.2
4.8 5.6 6.4
4
INPUT VOLTAGE (V)
7.2
8
22
3.2
4.8 5.6 6.4
4
INPUT VOLTAGE (V)
7.2
8
3534 G03
3534 G04
Minimum Start-Up Voltage
vs Temperature
2.200
ACTIVE QUIESCENT CURRENT (μA)
450
Active Quiescent Current
vs Temperature
V
FB
= 1.2V
Burst Mode SLEEP CURRENT (μA)
50
Burst Mode SLEEP Current
vs Temperature
V
FB
= 1.2V
V
IN
START VOLTAGE (V)
430
40
2.175
410
30
2.150
390
20
2.125
–50
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G05
370
–50
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G06
10
–50
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G07
3534f
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LTC3534
TYPICAL PERFORMANCE CHARACTERISTICS
Converter Line Regulation
vs Temperature
5.005
CONVERTER LINE REGULATION (V)
5.000
4.995
4.990
4.985
4.980
4.975
–50
3.6V
5.0V
6.4V
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G08
T
A
= 25°C, unless otherwise noted.
Converter Load Regulation
vs Temperature
5.01
CONVERTER LOAD REGULATION (V)
5.00
1.000
FB VOLTAGE (V)
4.99
4.98
500mA
4.97
4.96
4.95
–50
300mA
V
IN
= 5V
1.001
25mA
Feedback Voltage vs Temperature
I
LOAD
= 100mA
0.999
0.998
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G09
0.997
–50
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G10
Switching Frequency
vs Temperature
1050
3.0
2.8
1025
CURRENT LIMIT (A)
2.5
2.3
2.0
Current Limits vs Temperature
BURST NO-LOAD INPUT CURRENT (μA)
V
IN
= V
OUT
= 5V
50
BURST No-Load Input Current
vs V
IN
(Switching)
V
OUT
= 5V
SWITCHING FREQUENCY (kHz)
PEAK CURRENT LIMIT
45
1000
40
975
1.8
950
–50
1.5
–50
LINEAR CURRENT LIMIT
35
–25
0
50
25
TEMPERATURE (°C)
75
100
3534 G11
–25
25
0
50
TEMPERATURE (°C)
75
100
3534 G12
30
2.4
3.2
4
4.8 5.6 6.4
INPUT VOLTAGE (V)
7.2
8
3534 G13
PWM No-Load Input Current
vs V
IN
(Switching)
18
PWM NO-LOAD INPUT CURRENT (mA)
V
OUT
= 5V
OUTPUT CURRENT CAPABILITY (mA)
225
200
175
150
125
100
75
BURST Maximum Output Current
Capability vs V
IN
1800
OUTPUT CURRENT CAPABILITY (mA)
PWM Maximum Output Current
Capability vs V
IN
V
OUT
= 5V
1600 L = 4.7μH
1400
1200
1000
800
600
400
200
2.4
3.2
4.8 5.6 6.4
4
INPUT VOLTAGE (V)
7.2
8
14
10
6
2
2.4
3.2
4.8 5.6 6.4
4
INPUT VOLTAGE (V)
7.2
8
50
2.4
V
OUT
= 5V
Burst Mode OPERATION
3.2
4
4.8 5.6 6.4
INPUT VOLTAGE (V)
7.2
8
3534 G14
3534 G15
3534 G16
3534f
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