includes an accurate RUN pin threshold to allow predict-
able regulator 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 LTC3129-1 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. To further
reduce part count and improve light load efficiency, the
LTC3129-1 includes an internal voltage divider to provide
eight selectable fixed output voltages.
Additional features include a power good output, less than
10nA of shutdown current and thermal shutdown.
The LTC3129-1 is available in thermally enhanced
3mm × 3mm QFN and 16-lead MSOP packages. For an
adjustable output voltage, see the functionally equivalent
LTC3129.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective owners.
n
n
n
n
n
n
n
n
n
n
n
n
n
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)
Fixed Output Voltage with Eight User-Selectable
Settings from 2.5V to 15V
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
n
n
n
n
n
n
Typical applicaTion
22nF
10µH
22nF
V
IN
2.42V TO 15V
10µF
V
CC
BST1 SW1
V
IN
LTC3129-1
RUN
MPPC
PWM
VS1
VS2
VS3
GND
PGND
31291 TA01a
Efficiency and Power Loss vs Load
100
90
EFFICIENCY
100
POWER LOSS (mW)
10
POWER LOSS
1000
SW2 BST2
V
OUT
EFFICIENCY (%)
V
OUT
5V AT
10µF 100mA V
IN
< V
OUT
200mA V
IN
> V
OUT
80
70
60
50
40
30
20
PGOOD
1
AA OR AAA
BATTERIES
V
CC
2.2µF
V
IN
= 2.5V
0.1
V
IN
= 3.6V
V
IN
= 5V
10
V
IN
= 15V
V
OUT
= 5V
0.01
0
0.01
0.1
1
10
100
1000
OUTPUT CURRENT (mA)
3129 TA01b
31291fb
For more information
www.linear.com/LTC3129-1
1
LTC3129-1
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 Voltage................................. –0.3V to 18V
V
CC
, PWM, MPPC, VS1, VS2,
VS3 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
VS3
8
VS2
VS1
V
CC
RUN
MPPC
GND
VS3
VS2
VS1
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
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
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
orDer inForMaTion
LEAD FREE FINISH
LTC3129EUD-1#PBF
LTC3129IUD-1#PBF
LTC3129EMSE-1#PBF
LTC3129IMSE-1#PBF
TAPE AND REEL
LTC3129EUD-1#TRPBF
LTC3129IUD-1#TRPBF
LTC3129EMSE-1#TRPBF
LTC3129IMSE-1#TRPBF
PART MARKING*
LGDS
LGDS
31291
31291
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. *The temperature grade is identified by a label on the shipping container.
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/
2
31291fb
For more information
www.linear.com/LTC3129-1
LTC3129-1
elecTrical characTerisTics
PARAMETER
V
IN
Start-Up Voltage
Input Voltage Range
V
IN
UVLO Threshold (Rising)
V
IN
UVLO Hysteresis
V
OUT
Voltages
VS1 = VS2 = VS3 = 0V
VS1 = V
CC
, VS2 = VS3 = 0V
VS2 = V
CC
, VS1 = VS3 = 0V
VS1 = VS2 = V
CC
, VS3 = 0V
VS1 = VS2 = 0V, VS3 = V
CC
VS2 = 0V, VS1 = VS3 = V
CC
VS1 = 0V, VS2 = VS3 = V
CC
VS1 = VS2 = VS3 = V
CC
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
, V
OUT
> V
REG
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)
V
OUT
< V
REG
as Set by VS1-VS3. Percentage of
Period SW2 is Low in Boost Mode (Note 7)
V
OUT
> V
REG
as Set by VS1-VS3. Percentage of
Period SW1 is High in Buck Mode (Note 7)
PWM = V
CC
(Note 3)
l
l
l
l
l
l
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
l
l
l
l
l
l
TYP
2.25
MAX
2.42
15
2.0
130
2.575
3.383
4.203
5.125
7.073
8.405
12.40
15.50
100
3
2.0
50
UNITS
V
V
V
mV
V
V
V
V
V
V
V
V
nA
µA
µA
nA
V
CC
> 2.42V (Back-Driven)
V
CC
> 2.42V (Back-Driven)
1.92
1.8
80
2.425
3.2175
3.998
4.875
6.727
7.995
11.64
14.50
1.9
100
2.5
3.3
4.1
5.0
6.9
8.2
12
15.0
10
1.9
1.3
10
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
VS1, VS2, VS3 Input High
VS1, VS2, VS3 Input Low
VS1, VS2, VS3 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
)
0.75
220
80
400
85
275
130
500
89
350
200
680
95
0
1.0
1.12
0.5
1.16
50
1.2
90
1.175
1
l
Ω
mA
mA
mA
%
%
MHz
ns
1.22
10
1.15
1.28
120
10
0.4
V
nA
V
V
mV
nA
V
V
nA
V
0.5
V
µA
ms
4.7
60
2
V
mV
mV
31291fb
1.4
MPPC = 5V
V
CC
> 2.4V
RUN = 15V
l
l
l
0.9
1.22
80
1
1.2
1
10
VS1, VS2, VS3 = V
CC
= 5V
l
l
1.6
0.1
3
1
PWM = 5V
V
IN
> 4.85V
V
IN
= 3.0V, Switching
V
IN
= 2.0V (V
CC
in UVLO)
l
3.4
4.1
35
0
For more information
www.linear.com/LTC3129-1
3
LTC3129-1
elecTrical characTerisTics
PARAMETER
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
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, V
OUT
≥ V
REG
PWM = V
CC
, V
OUT
= 15V (Note 4)
Referenced to Programmed V
OUT
Voltage
Referenced to Programmed V
OUT
Voltage
I
SINK
= 1mA
PGOOD = 15V
–5.5
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
2.1
4
TYP
2.25
60
20
2
–27
MAX
2.42
40
5.5
4
1.35
100
9
–10
300
50
UNITS
V
mV
mA
V
mA
µA
V
mV
nA
µA
µA
%
%
mV
nA
V
CC
= 0V
l
l
0.95
1.15
150
10
V
OUT
/27
5
–7.5
2.5
250
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 LTC3129-1 is tested under pulsed load conditions such
that T
J
≈ T
A
. The LTC3129E-1 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-1 is guaranteed over the full –40°C to 125°C operating junction
temperature range. The junction temperature (T
J
, in °C) is calculated from
the ambient temperature (T
A
, in °C) and power dissipation (P
D
, in watts)
according to the formula:
T
J
= T
A
+ (P
D
•
θ
JA
),
where
θ
JA
(in °C/W) 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.
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