FeaTures
n
n
LTC3129
15V, 200mA Synchronous
Buck-Boost DC/DC Converter
with 1.3µA Quiescent Current
DescripTion
The
LTC
®
3129
is a high efficiency, 200mA buck-boost
DC/DC converter with a wide V
IN
and V
OUT
range. It includes
an accurate RUN pin threshold to allow predictable regula-
tor turn-on and a maximum power point control (MPPC)
capability that ensures maximum power extraction from
non-ideal power sources such as photovoltaic panels.
The LTC3129 employs an ultralow noise, 1.2MHz PWM
switching architecture that minimizes solution footprint by
allowing the use of tiny, low profile inductors and ceramic
capacitors. Built-in loop compensation and soft-start
simplify the design. For high efficiency operation at light
loads, automatic Burst Mode operation can be selected,
reducing the quiescent current to just 1.3µA.
Additional features include a power good output, less than
10nA of shutdown current and thermal shutdown.
The LTC3129 is available in thermally enhanced 3mm ×
3mm QFN and 16-lead MSOP packages. For fixed output
voltage options, see the functionally equivalent LTC3129-1,
which eliminates the need for an external feedback divider.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
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Regulates V
OUT
Above, Below or Equal to V
IN
Wide V
IN
Range: 2.42V to 15V, 1.92V to 15V After
Start-Up (Bootstrapped)
Wide V
OUT
Range: 1.4V to 15.75V
200mA Output Current in Buck Mode
Single Inductor
1.3µA Quiescent Current
Programmable Maximum Power Point Control
1.2MHz Ultralow Noise PWM
Current Mode Control
Pin Selectable Burst Mode
®
Operation
Up to 95% Efficiency
Accurate RUN Pin Threshold
Power Good Indicator
10nA Shutdown Current
Thermally Enhanced 3mm × 3mm QFN and
16-Lead MSOP Packages
Industrial Wireless Sensor Nodes
Post-Regulator for Harvested Energy
Solar Panel Post-Regulator/Charger
Intrinsically Safe Power Supplies
Wireless Microphones
Avionics-Grade Wireless Headsets
applicaTions
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Typical applicaTion
22nF
10µH
22nF
5V AT 200mA, V
IN
> 5V
5V AT 100mA, V
IN
< 5V
V
OUT
EFFICIENCY (%)
10µF
3.32M
FB
PGOOD
V
CC
GND
PGND
2.2µF
1.02M
10pF
100
90
80
70
60
50
40
30
20
POWER LOSS
10
EFFICIENCY
100
POWER LOSS (mW)
Efficiency and Power Loss vs Load
1000
2.42V TO 15V
V
IN
BST1 SW1
V
IN
SW2 BST2
V
OUT
LTC3129
RUN
10µF
V
CC
MPPC
PWM
1
V
IN
= 2.5V
0.1
V
IN
= 3.6V
V
IN
= 5V
10
V
IN
= 15V
V
OUT
= 5V
0
0.01
0.01
0.1
1
10
100
1000
OUTPUT CURRENT (mA)
3129 TA01b
3129 TA01a
3129fc
For more information
www.linear.com/LTC3129
1
LTC3129
absoluTe MaxiMuM raTings
(Notes 1, 8)
V
IN
, V
OUT
Voltages .................................... –0.3V to 18V
SW1 DC Voltage............................ –0.3V to (V
IN
+ 0.3V)
SW2 DC Voltage..........................–0.3V to (V
OUT
+ 0.3V)
SW1, SW2 Pulsed (<100ns) Voltage ..............–1V to 19V
BST1 Voltage .................... (SW1 – 0.3V) to (SW1 + 6V)
BST2 Voltage ....................(SW2 – 0.3V) to (SW2 + 6V)
RUN, PGOOD Voltages ............................... –0.3V to 18V
V
CC
, FB, PWM, MPPC Voltages.................... –0.3V to 6V
PGOOD Sink Current .............................................15mA
Operating Junction Temperature Range
(Notes 2, 5) ............................................ –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
MSE Lead Temperature (Soldering, 10 sec) .......... 300°C
pin conFiguraTion
TOP VIEW
PGND
BST2
SW1
SW2
TOP VIEW
12 V
OUT
17
PGND
11 PGOOD
10 PWM
9
5
MPPC
6
GND
7
FB
8
NC
NC
V
CC
RUN
MPPC
GND
FB
NC
NC
PWM
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
IN
BST1
SW1
PGND
SW2
BST2
V
OUT
PGOOD
16 15 14 13
BST1 1
V
IN
2
V
CC
3
RUN 4
17
PGND
MSE PACKAGE
16-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JC
= 10°C/W,
θ
JA
= 40°C/W (NOTE 6)
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
UD PACKAGE
16-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JC
= 7.5°C/W,
θ
JA
= 68°C/W (NOTE 6)
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3129EUD#PBF
LTC3129IUD#PBF
LTC3129EMSE#PBF
LTC3129IMSE#PBF
TAPE AND REEL
LTC3129EUD#TRPBF
LTC3129IUD#TRPBF
LTC3129EMSE#TRPBF
LTC3129IMSE#TRPBF
PART MARKING*
LGDR
LGDR
3129
3129
PACKAGE DESCRIPTION
16-Lead (3mm × 3mm) Plastic QFN
16-Lead (3mm × 3mm) Plastic QFN
16-Lead Plastic MSOP
16-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
2
3129fc
For more information
www.linear.com/LTC3129
LTC3129
elecTrical characTerisTics
PARAMETER
V
IN
Start-Up Voltage
Input Voltage Range
V
IN
UVLO Threshold (Rising)
V
IN
UVLO Hysteresis
Output Voltage Adjust Range
Feedback Voltage
Feedback Input Current
Quiescent Current (V
IN
) – Shutdown
Quiescent Current (V
IN
) UVLO
Quiescent Current – Burst Mode Operation
N-Channel Switch Leakage on V
IN
and V
OUT
N-Channel Switch On-Resistance
Inductor Average Current Limit
Inductor Peak Current Limit
Maximum Boost Duty Cycle
Minimum Duty Cycle
Switching Frequency
SW1 and SW2 Minimum Low Time
MPPC Voltage
MPPC Input Current
RUN Threshold to Enable V
CC
RUN Threshold to Enable Switching (Rising)
RUN (Switching) Threshold Hysteresis
RUN Input Current
PWM Input High
PWM Input Low
PWM Input Current
Soft-Start Time
V
CC
Voltage
V
CC
Dropout Voltage (V
IN
– V
CC
)
V
CC
UVLO Threshold (Rising)
V
CC
UVLO Hysteresis
V
CC
Current Limit
V
CC
Back-Drive Voltage (Maximum)
V
CC
Input Current (Back-Driven)
V
CC
Leakage to V
IN
if V
CC
> V
IN
V
OUT
UV Threshold (Rising)
V
CC
= 5.5V (Switching)
V
CC
= 5.5V, V
IN
= 1.8V, Measured on V
IN
l
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). Unless otherwise noted, V
IN
= 12V, V
OUT
= 5V.
CONDITIONS
l
MIN
l
l
l
l
l
TYP
2.25
MAX
2.42
15
2.0
130
15.75
1.199
10
100
3
2.0
50
UNITS
V
V
V
mV
V
V
nA
nA
µA
µA
nA
Ω
V
CC
> 2.42V (Back-Driven)
V
CC
> 2.42V (Back-Driven)
1.92
1.8
80
1.4
1.151
1.175
0.1
10
1.9
1.3
10
0.75
1.9
100
FB = 1.25V
RUN = 0V, Including Switch Leakage
Either V
IN
or V
CC
Below Their UVLO Threshold, or
RUN Below the Threshold to Enable Switching
Measured on V
IN
, FB > 1.25V
PWM = 0V, RUN = V
IN
SW1 = 0V, V
IN
= 15V
SW2 = 0V, V
OUT
= 15V
RUN = 0V
V
CC
= 4V
V
OUT
> UV Threshold (Note 4)
V
OUT
< UV Threshold (Note 4)
(Note 4)
FB = 1.10V. Percentage of Period SW2 is Low in
Boost Mode (Note 7)
FB = 1.25V. Percentage of Period SW1 is High in
Buck Mode (Note 7)
PWM = V
CC
(Note 3)
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l
l
l
l
l
l
220
80
400
85
275
130
500
89
350
200
680
95
0
mA
mA
mA
%
%
MHz
ns
V
nA
V
V
mV
nA
V
V
µA
ms
V
mV
mV
V
mV
mA
V
mA
µA
V
3129fc
1.0
1.12
0.5
1.16
50
1.2
90
1.175
1
0.9
1.22
80
1
1.4
1.22
10
1.15
1.28
120
10
0.5
MPPC = 5V
l
V
CC
> 2.4V
RUN = 15V
l
l
l
1.6
0.1
3
1
4.7
60
2
2.42
60
5.5
2
–27
0.95
1.15
1.35
4
PWM = 5V
V
IN
> 4.85V
V
IN
= 3.0V, Switching
V
IN
= 2.0V (V
CC
in UVLO)
l
l
3.4
4.1
35
0
2.1
4
2.25
60
20
V
CC
= 0V
l
l
For more information
www.linear.com/LTC3129
3
LTC3129
elecTrical characTerisTics
PARAMETER
V
OUT
UV Hysteresis
V
OUT
Current – Shutdown
V
OUT
Current – Sleep
V
OUT
Current – Active
PGOOD Threshold, Falling
PGOOD Hysteresis
PGOOD Voltage Low
PGOOD Leakage
RUN = 0V, V
OUT
= 15V Including Switch Leakage
PWM = 0V, FB = 1.25V
PWM = V
CC
, V
OUT
= 15V (Note 4), FB = 1.25V
Referenced to Programmed V
OUT
Voltage
Referenced to Programmed V
OUT
Voltage
I
SINK
= 1mA
PGOOD = 15V
–5.5
CONDITIONS
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). Unless otherwise noted, V
IN
= 12V, V
OUT
= 5V.
MIN
TYP
150
10
10
5
–7.5
2.5
250
1
300
50
9
–10
100
MAX
UNITS
mV
nA
nA
µA
%
%
mV
nA
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 LTC3129 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3129E is guaranteed to meet specifications from
0°C to 85°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3129I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The junction temperature (T
J
) is calculated from the
ambient temperature (T
A
) and power dissipation (P
D
) according to the
formula: T
J
= T
A
+ (P
D
•
θ
JA
°C/W), where
θ
JA
is the package thermal
impedance. Note that the maximum ambient temperature consistent
with these specifications, is determined by specific operating conditions
in conjunction with board layout, the rated thermal package thermal
resistance and other environmental factors.
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 much higher thermal resistance.
Note 7:
Switch timing measurements are made in an open-loop test
configuration. Timing in the application may vary somewhat from these
values due to differences in the switch pin voltage during non-overlap
durations when switch pin voltage is influenced by the magnitude and
duration of the inductor current.
Note 8:
Voltage transients on the switch pin(s) beyond the DC limits
specified in the Absolute Maximum Ratings are non-disruptive to normal
operation when using good layout practices as described elsewhere in the
data sheet and application notes and as seen on the product demo board.
Typical perForMance characTerisTics
Efficiency, V
OUT
= 2.5V
100
90
80
POWER LOSS (mW)
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
PWM
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G01
T
A
= 25°C, unless otherwise noted.
Efficiency, V
OUT
= 3.3V
100
90
BURST
Power Loss, V
OUT
= 2.5V
1000
BURST
100
PWM
EFFICIENCY (%)
80
70
60
50
40
30
20
10
0
0.01
0.1
PWM
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G03
10
1
BURST
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1000
3129 G02
0.1
0.01
0.01
0.1
1
100
10
OUTPUT CURRENT (mA)
4
3129fc
For more information
www.linear.com/LTC3129
LTC3129
Typical perForMance characTerisTics
Power Loss, V
OUT
= 3.3V
1000
100
90
100
POWER LOSS (mW)
PWM
EFFICIENCY (%)
80
POWER LOSS (mW)
70
60
50
40
30
20
10
0
0.01
0.1
PWM
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G05
T
A
= 25°C, unless otherwise noted.
Efficiency, V
OUT
= 5V
BURST
1000
Power Loss, V
OUT
= 5V
PWM
100
10
10
1
BURST
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1000
3129 G04
1
BURST
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1000
3129 G06
0.1
0.1
0.01
0.01
0.1
1
100
10
OUTPUT CURRENT (mA)
0.01
0.01
0.1
1
100
10
OUTPUT CURRENT (mA)
100
90
80
Efficiency, V
OUT
= 12V
BURST
40
1000
Power Loss, V
OUT
= 12V
100
PWM
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
Efficiency, V
OUT
= 15V
BURST
100
POWER LOSS (mW)
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
PWM
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G07
10
BURST
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
0.1
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G08
1
PWM
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
0.1
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G09
0.1
0.01
0.01
0
0.01
Power Loss, V
OUT
= 15V
1000
PWM
250
Maximum Output Current
vs V
IN
and V
OUT
30
25
20
I
IN
(µA)
No Load Input Current
vs V
IN
and V
OUT
(PWM = 0V)
V
OUT
= 2.5V
V
OUT
= 5V
V
OUT
= 10V
V
OUT
= 15V
FB DIVIDER CURRENT = 2µA
100
POWER LOSS (mW)
200
I
OUT
(mA)
10
BURST
V
IN
= 2.5V
V
IN
= 3.6V
V
IN
= 5V
V
IN
= 10V
V
IN
= 15V
0.1
1
100
10
OUTPUT CURRENT (mA)
1000
3129 G10
150
V
OUT
= 2.5V
V
OUT
= 3.3V
V
OUT
= 4.1V
V
OUT
= 5V
V
OUT
= 6.9V
V
OUT
= 8.2V
V
OUT
= 12V
V
OUT
= 15V
2 3 4 5 6 7 8 9 10 11 12 13 14 15
V
IN
(V)
3129 G11
15
10
5
0
2.5
1
100
0.1
50
0.01
0.01
0
4.5
6.5
8.5 10.5
V
IN
(V)
12.5
14.5
3129 G12
3129fc
For more information
www.linear.com/LTC3129
5
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