LTC3105
400mA Step-Up DC/DC
Converter with Maximum Power
Point Control and 250mV Start-Up
FEATURES
DESCRIPTION
Low Start-Up Voltage: 250mV
n Maximum Power Point Control
n Wide V Range: 225mV to 5V
IN
n Auxiliary 6mA LDO Regulator
n Burst Mode® Operation: I = 24µA
Q
n Output Disconnect and Inrush Current Limiting
n V > V
IN
OUT Operation
n Antiringing Control
n Soft Start
n Automatic Power Adjust
n Power Good Indicator
n 10-Lead 3mm × 3mm × 0.75mm DFN and 12-Lead
MSOP Packages
The LTC®3105 is a high efficiency step-up DC/DC converter
that can operate from input voltages as low as 225mV. A
250mV start-up capability and integrated maximum power
point controller (MPPC) enable operation directly from low
voltage, high impedance alternative power sources such as
photovoltaic cells, TEGs (thermoelectric generators) and
fuel cells. A user programmable MPPC set point maximizes
the energy that can be extracted from any power source.
Burst Mode operation, with a proprietary self adjusting
peak current, optimizes converter efficiency and output
voltage ripple over all operating conditions.
n
The AUX powered 6mA LDO provides a regulated rail for
external microcontrollers and sensors while the main
output is charging. In shutdown, IQ is reduced to 10µA
and integrated thermal shutdown offers protection from
overtemperature faults. The LTC3105 is offered in 10-lead
3mm × 3mm × 0.75mm DFN and 12-lead MSOP packages.
APPLICATIONS
n
n
n
n
n
Solar Powered Battery/Supercapacitor Chargers
Energy Harvesting
Remote Industrial Sensors
Low Power Wireless Transmitters
Cell Phone, MP3, PMP and GPS Accessory Chargers
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT and PowerPath are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATION
Single Photovoltaic Cell Li-Ion Trickle Charger
Output Current vs Input Voltage
80
10µH
MPPC DISABLED
225mV TO 5V
PHOTOVOLTAIC
CELL
VIN
+
–
SW
VOUT
4.1V
VOUT
10µF
LTC3105
1020k
FB
OFF ON
40.2k
1µF
MPPC
PGOOD
SHDN
LDO
AUX
Li-Ion
332k
2.2V
10µF
OUTPUT CURRENT (mA)
70
FBLDO
GND
VOUT = 3.3V
60
50
VOUT = 4.2V
40
VOUT = 5V
30
20
10
4.7µF
0
3105 TA01a
0.2
0.3
0.4 0.5 0.6 0.7 0.8
INPUT VOLTAGE (V)
0.9
1.0
3105 TA01b
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1
LTC3105
ABSOLUTE MAXIMUM RATINGS
(Note 1)
SW Voltage
DC............................................................. –0.3V to 6V
Pulsed ( VLDO
l
1.4
LDO Output Voltage
VFBLDO = 0V
l
2.148
2.2
2.236
V
Feedback Voltage (FBLDO Pin)
External Feedback Network
l
0.984
1.004
1.024
V
Load Regulation
ILDO = 1mA to 6mA
0.40
Line Regulation
VAUX = 2.5V to 5V
0.15
%
Dropout Voltage
ILDO = 6mA, VOUT = VAUX = 2.2V
105
mV
LDO Current Limit
VLDO 0.5V Below Regulation Voltage
12
mA
LDO Reverse-Blocking Leakage Current
VIN = VAUX = VOUT = 0V, VSHDN = 0V
1
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 LTC3105 is tested under pulsed load conditions such that
TJ ≈ TA. The LTC3105E is guaranteed to meet specifications from
0°C to 85°C junction temperature. Specifications over the –40°C to 85°C
operating junction temperature range are assured by design, characterization and correlation with statistical process controls. Note that the
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors.
l
6
%
Note 3: Current measurements are performed when the LTC3105 is not
switching. The current limit values measured in operation will be somewhat
higher due to the propagation delay of the comparators.
Note 4: This IC includes over temperature 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 5: The LTC3105 has been optimized for use with high impedance
power sources such as photovoltaic cells and thermoelectric generators.
The input start-up voltage is measured using an input voltage source with
a series resistance of approximately 200mΩ and MPPC enabled. Use of the
LTC3105 with lower resistance voltage sources or with MPPC disabled may
result in a higher input start-up voltage.
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3
LTC3105
T
TYPICAL
PERFORMANCE CHARACTERISTICS A = 25°C, VAUX = VOUT = 3.3V, VLDO = 2.2V,
VIN = 0.6V, unless otherwise noted.
Minimum Input Start-Up Voltage
vs Temperature
Shutdown Thresholds
vs Input Voltage
340
900
300
280
260
240
220
IC Enable Delay vs Input Voltage
IC ENABLE
800
100
700
600
DELAY TIME (µs)
THRESHOLD VOLTAGE (mV)
INPUT VOLTAGE (mV)
320
200
–45 –30 –15
120
1000
IC DISABLE
500
400
300
80
60
200
100
0 15 30 45 60
TEMPERATURE (°C)
0
1.25
75 90
3105 G01
2.25
4.25
3.25
SUPPLY VOLTAGE, VIN OR VAUX (V)
MPPC Current Variation
vs Temperature
SOFT-START TIME (ms)
CHANGE FROM 25°C (%)
2.25
4.25
3.25
SUPPLY VOLTAGE, VIN OR VAUX (V)
5.25
3105 G03
1.20
1.5
1.0
0.5
0
–0.5
1.15
1.10
1.05
1.00
–1.0
–1.5
–45 –30 –15
0 15 30 45 60
TEMPERATURE (°C)
0.95
75 90
6
3
4
5
2
LDO LOAD CURRENT (mA)
3105 G06
VIN for Synchronous Operation
5.0
SHDN = 0V
MAXIMUM INPUT VOLTAGE (V)
4.5
18
16
14
12
10
8
6
4
–45 –30 –15
1
3105 G05
VOUT IQ vs Temperature
During Shutdown
IQ (µA)
3105 G02
1.25
2.0
20
40
1.25
LDO Soft-Start Duration
vs LDO Load
2.5
22
5.25
NONSYNCHRONOUS
OPERATION
4.0
3.5
3.0
2.5
2.0
SYNCHRONOUS
OPERATION
1.5
1.0
0.5
0 15 30 45 60
TEMPERATURE (°C)
75 90
0
1.5
2.0
3105 G07
2.5 3.0 3.5 4.0 4.5
OUTPUT VOLTAGE (V)
5.0
5.5
3105 G09
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LTC3105
T
TYPICAL
PERFORMANCE CHARACTERISTICS A = 25°C, VAUX = VOUT = 3.3V, VLDO = 2.2V,
VIN = 0.6V, unless otherwise noted.
Exiting MPPC Control on
Input Voltage Step
IPEAK and IVALLEY Current Limit
Change vs Temperature
100
IPEAK
CHANGE FROM 25°C (%)
0.5
INDUCTOR
CURRENT
100mA/DIV
MPPC VOLTAGE
200mV/DIV
90
0
EFFICIENCY (%)
VMPPC = 400mV
VIN VOLTAGE
200mV/DIV
Efficiency vs VIN
1.0
IVALLEY
–0.5
–1.0
–1.5
–2.5
–45 –30 –15
3105 G10
0 15 30 45 60
TEMPERATURE (°C)
60
VIN = 0.6V
VIN = 0.8V
VIN = 1V
70
1000
EFFICIENCY
100
60
50
10
40
POWER LOSS
30
1
20
INPUT
VOLTAGE
5mV/DIV
5.25
3105 G12
POWER LOSS (mW)
EFFICIENCY (%)
2.25
3.25
4.25
INPUT VOLTAGE (V)
Efficiency vs Output Current and
Power Loss, VOUT = 3.3V
80
SW CURRENT
200mA/DIV
1.25
3105 G11
90
VOUT = 3.3V
IOUT = 15mA
COUT = 10µF
OUTPUT
VOLTAGE
50mV/DIV
10
50µs/DIV
0
0.01
3105 G13
90
1000
VIN = 3V
VIN = 2V
VIN = 1.5V
10
50
POWER LOSS
1
0.1
100
3105 G14
800
VOUT = 3.3V
600
500
400
300
200
100
30
20
0.01
POWER LOSS (mW)
100
EFFICIENCY
60
40
10
700
80
70
1
No-Load Input Current
vs Input Voltage
INPUT CURRENT (µA)
100
0.1
OUTPUT CURRENT (mA)
Efficiency vs Output Current and
Power Loss, VOUT = 5V
EFFICIENCY (%)
70
40
0.25
75 90
Input and Output Burst Ripple
VIN = 0.6V
CIN = 470µF
80
50
–2.0
15µs/DIV
VOUT = 3V
ILOAD = 10mA
LDO = 2.2V
1
10
0.1
OUTPUT CURRENT (mA)
0.1
100
0
0.2
3105 G15
0.4
0.6
0.8
INPUT VOLTAGE (V)
1.0
1.2
3105 G16
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5
LTC3105
PIN FUNCTIONS
(DFN/MSOP)
FB (Pin 1/Pin 1): Step-Up Converter Feedback Input.
Connect the VOUT resistor divider tap to this input. The
output voltage can be adjusted between 1.6V and 5.25V.
LDO (Pin 2/Pin 2): LDO Regulator Output. Connect a 4.7µF
or larger capacitor between LDO and GND.
FBLDO (Pin 3/Pin 3): LDO Feedback Input. Connect the
LDO resistive divider tab to this input. Alternatively, connecting FBLDO directly to GND will configure the LDO
output voltage to be internally set at 2.2V (nominal).
SHDN (Pin 4/Pin 4): Logic Controlled Shutdown Input.
With SHDN open, the converter is enabled by an internal
2MΩ pull-up resistor. The SHDN pin should be driven with
an open-drain or open-collector pull-down and floated until
the converter has entered normal operation. Excessive
loading on this pin may cause a failure to complete start-up.
SHDN = Low: IC Disabled
SHDN = High: IC Enabled
MPPC (Pin 5/Pin 5): Set Point Input for Maximum
Power Point Control. Connect a resistor from MPPC to
GND to program the activation point for the MPPC loop.
To disable the MPPC circuit, connect MPPC directly
to GND.
VIN (Pin 6/Pin 8): Input Supply. Connect a decoupling
capacitor between this pin and GND. The PCB trace length
from the VIN pin to the decoupling capacitor should be as
short and wide as possible. When used with high impedance sources such as photovoltaic cells, this pin should
have a 10µF or larger decoupling capacitor.
GND (Exposed Pad Pin 11/Pins 6, 7) : Small Signal and
Power Ground for the IC. The GND connections should be
soldered to the PCB ground using the lowest impedance
path possible.
SW (Pin 7/Pin 9): Switch Pin. Connect an inductor between
SW and VIN. PCB trace lengths should be as short as possible to reduce EMI. While the converter is sleeping or is
in shutdown, the internal antiringing switch connects the
SW pin to the VIN pin in order to minimize EMI.
PGOOD (Pin 8/Pin 10): Power Good Indicator. This is an
open-drain output. The pull-down is disabled when VOUT
has achieved the voltage defined by the feedback divider
on the FB pin. The pull-down is also disabled while the IC
is in shutdown or start-up mode.
VOUT (Pin 9/Pin 11): Step-Up Converter Output. This is the
drain connection of the main output internal synchronous
rectifier. A 10µF or larger capacitor must be connected
between this pin and GND. The PCB trace length from the
VOUT pin to the output filter capacitor should be as short
and wide as possible.
AUX (Pin 10/Pin 12): Auxiliary Voltage. Connect a 1µF
capacitor between this pin and GND. This pin is used by
the start-up circuitry to generate a voltage rail to power
internal circuitry until the main output reaches regulation.
AUX and VOUT are internally connected together once VOUT
exceeds VAUX.
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LTC3105
BLOCK DIAGRAM
(Pin Numbers for DFN Package Only)
L1
10µH
7
SHUTDOWN
SLEEP
SW
OR
WELL
CONTROL
AUX
VIN
LOW VOLTAGE
START-UP
CURRENT
ADJUST
CIN
10µF
SHUTDOWN
VCC
5
VIN
RMPPC
VCC
4
– +
–g
m
+
1.6V TO
5.25V
COUT
10µF
9
2
CLDO
4.7µF
PEAK CURRENT
LIMIT
SHUTDOWN
VALLEY CURRENT LIMIT
LOGIC
2M
USER SHUTDOWN
SLEEP
BURST
CONTROL
–
+
VIN
VAUX
CAUX
1µF
10µA
MPPC
SHDN
– +
VOUT
LDO
VAUX
VCC
FBLDO
1.004V
FB
PGOOD
1.004V
FB
0.9V
EXPOSED PAD
11
+
–
6
– +
225mV
TO 5V
SHORT
CONTROL
10
R3
R1
R4
R2
3
1
8
SLEEP
3105 BD
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7
LTC3105
OPERATION
Introduction
The LTC3105 is a unique, high performance, synchronous
boost converter that incorporates maximum power point
control, 250mV start-up capability and an integrated LDO
regulator. This part operates over a very wide range of input
voltages from 225mV to 5V. Its Burst Mode architecture
and low 24µA quiescent current optimize efficiency in low
power applications.
An integrated maximum power point controller allows for
operation directly from high impedance sources such as
photovoltaic cells by preventing the input power source
voltage from collapsing below the user programmable
MPPC threshold. Peak current limits are automatically
adjusted with proprietary techniques to maintain operation
at levels that maximize power extraction from the source.
The 250mV start-up voltage and 225mV minimum
operating voltage enable direct operation from a single
photovoltaic cell and other very low voltage, high series
impedance power sources such as TEGs and fuel cells.
Synchronous rectification provides high efficiency operation while eliminating the need for external Schottky diodes.
The LTC3105 provides output disconnect which prevents
large inrush currents during start-up. This is particularly
important for high internal resistance power sources like
photovoltaic cells and thermoelectric generators which
can become overloaded if inrush current is not limited
during start-up of the power converter. In addition, output
disconnect isolates VOUT from VIN while in shutdown.
VIN > VOUT Operation
The LTC3105 includes the ability to seamlessly maintain
regulation if VIN becomes equal to or greater than VOUT .
With VIN greater than or equal to VOUT , the synchronous rectifiers are disabled which may result in reduced
efficiency.
Shutdown Control
The SHDN pin is an active low input that places the IC
into low current shutdown mode. This pin incorporates an
internal 2MΩ pull-up resistor which enables the converter
if the SHDN pin is not controlled by an external circuit. The
SHDN pin should be allowed to float while the part is in
start-up mode. Once in normal operation, the SHDN pin
may be controlled using an open-drain or open-collector
pull-down. Other external loads on this pin should be
avoided, as they may result in the part failing to reach
regulation. In shutdown, the internal switch connecting
AUX and VOUT is enabled.
When the SHDN pin is released, the LTC3105 is enabled
and begins switching after a short delay. When either VIN
or VAUX is above 1.4V, this delay will typically range between 20µs and 100µs. Refer to the Typical Performance
Characteristics section for more details.
Start-Up Mode Operation
The LTC3105 provides the capability to start with voltages
as low as 250mV. During start-up the AUX output initially
is charged with the synchronous rectifiers disabled. Once
VAUX has reached approximately 1.4V, the converter leaves
start-up mode and enters normal operation. Maximum
power point control is not enabled during start-up, however,
the currents are internally limited to sufficiently low levels
to allow start-up from weak input sources.
While the converter is in start-up mode, the internal switch
between AUX and VOUT remains disabled and the LDO
is disabled. Refer to Figure 1 for an example of a typical
start-up sequence.
The LTC3105 is optimized for use with high impedance
power sources such as photovoltaic cells. For operation
from very low impedance, low input voltage sources, it may
be necessary to add several hundred milliohms of series
input resistance to allow for proper low voltage start-up.
Normal Operation
When either VIN or VAUX is greater than 1.4V typical, the
converter will enter normal operation.
The converter continues charging the AUX output until
the LDO output enters regulation. Once the LDO output
is in regulation, the converter begins charging the VOUT
pin. VAUX is maintained at a level sufficient to ensure the
LDO remains in regulation. If VAUX becomes higher than
required to maintain LDO regulation, charge is transferred
from the AUX output to the VOUT output. If VAUX falls too
low, current is redirected to the AUX output instead of
being used to charge the VOUT output. Once VOUT rises
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LTC3105
INDUCTOR CURRENT
OPERATION
OUTPUT VOLTAGE
TIME
VAUX
VLDO
VOUT
1.4V
VOUT IN
REGULATION
LDO IN
REGULATION
START-UP MODE NORMAL OPERATION
TIME
VOUT = VAUX
VOUT SYNCHRONOUS
RECTIFIER ENABLED
3105 F01
Figure 1. Typical Converter Start-Up Sequence
above VAUX , an internal switch is enabled to connect the
two outputs together.
If VIN is greater than the voltage on the driven output (VOUT
or VAUX), or the driven output is less than 1.2V (typical),
the synchronous rectifiers are disabled. With the synchronous rectifiers disabled, the converter operates in critical
conduction mode. In this mode, the N-channel MOSFET
between SW and GND is enabled and remains on until the
inductor current reaches the peak current limit. It is then
disabled and the inductor current discharges completely
before the cycle is repeated.
When the output voltage is greater than the input voltage
and greater than 1.2V, the synchronous rectifier is enabled.
In this mode, the N-channel MOSFET between SW and
GND is enabled until the inductor current reaches the peak
current limit. Once current limit is reached, the N-channel
MOSFET turns off and the P-channel MOSFET between SW
and the driven output is enabled. This switch remains on
until the inductor current drops below the valley current
limit and the cycle is repeated.
When VOUT reaches the regulation point, the N- and Pchannel MOSFETs connected to the SW pin are disabled
and the converter enters sleep.
Auxiliary LDO
The integrated LDO provides a regulated 6mA rail to
power microcontrollers and external sensors. When the
input voltage is above the minimum of 225mV, the LDO is
powered from the AUX output allowing the LDO to attain
regulation while the main output is still charging. The LDO
has a 12mA current limit and an internal 1ms soft-start
to eliminate inrush currents. The LDO output voltage is
set by the FBLDO pin. If a resistor divider is connected
to this pin, the ratio of the resistors determines the LDO
output voltage. If the FBLDO pin is connected directly to
GND, the LDO will use a 2MΩ internal divider network to
program a 2.2V nominal output voltage. The LDO should
be programmed for an output voltage less than the programmed VOUT .
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LTC3105
OPERATION
When the converter is placed in shutdown mode, the LDO
is forced into reverse-blocking mode with reverse current
limited to under 1µA. After the shutdown event has ended,
the LDO remains in reverse-blocking mode until VAUX has
risen above the LDO voltage.
MPPC Operation
The maximum power point control circuit allows the user
to set the optimal input voltage operating point for a given
power source. The MPPC circuit dynamically regulates
the average inductor current to prevent the input voltage
from dropping below the MPPC threshold. When VIN is
greater than the MPPC voltage, the inductor current is
increased until VIN is pulled down to the MPPC set point.
If VIN is less than the MPPC voltage, the inductor current
is reduced until VIN rises to the MPPC set point.
Automatic Power Adjust
The LTC3105 incorporates a feature that maximizes efficiency at light load while providing increased power
capability at heavy load by adjusting the peak and valley
of the inductor current as a function of load. Lowering the
peak inductor current to 100mA at light load optimizes
efficiency by reducing conduction losses. As the load
increases, the peak inductor current is automatically increased to a maximum of 500mA. At intermediate loads,
the peak inductor current can vary between 100mA to
500mA. This function is overridden by the MPPC function
and will only be observed when the power source can
deliver more power than the load requires.
PGOOD Operation
The power good output is used to indicate that VOUT is
in regulation. PGOOD is an open-drain output, and is
disabled in shutdown. PGOOD will indicate that power
is good at the beginning of the first sleep event after
the output voltage has risen above 90% of its regulation
value. PGOOD remains asserted until VOUT drops below
90% of its regulation value at which point PGOOD will
pull low.
APPLICATIONS INFORMATION
Component Selection
Low DCR power inductors with values between 4.7µH
and 30µH are suitable for use with the LTC3105. For
most applications, a 10µH inductor is recommended. In
applications where the input voltage is very low, a larger
value inductor can provide higher efficiency and a lower
start-up voltage. In applications where the input voltage
is relatively high (VIN > 0.8V), smaller inductors may be
used to provide a smaller overall footprint. In all cases,
the inductor must have low DCR and sufficient saturation
current rating. If the DC resistance of the inductor is too
high, efficiency will be reduced and the minimum operating
voltage will increase.
Input capacitor selection is highly important in low voltage,
high source resistance systems. For general applications,
a 10µF ceramic capacitor is recommended between VIN
and GND. For high impedance sources, the input capacitor
should be large enough to allow the converter to complete
start-up mode using the energy stored in the input capacitor. When using bulk input capacitors that have high
ESR, a small valued parallel ceramic capacitor should be
placed between VIN and GND as close to the converter
pins as possible.
A 1µF ceramic capacitor should be connected between
AUX and GND. Larger capacitors should be avoided to
minimize start-up time. A low ESR output capacitor should
be connected between VOUT and GND. The main output
capacitor should be 10µF or larger. The main output can
also be used to charge energy storage devices including
tantalum capacitors, supercapacitors and batteries. When
using output bulk storage devices with high ESR, a small
valued ceramic capacitor should be placed in parallel and
located as close to the converter pins as possible.
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LTC3105
APPLICATIONS INFORMATION
Step-Up Converter Feedback Configuration
MPPC Threshold Configuration
A resistor divider connected between the VOUT and FB pins
programs the step-up converter output voltage, as shown
in Figure 2. An optional 22pF feedforward capacitor, CFF1,
can be used to reduce output ripple and improve load
transient response. The equation for VOUT is:
The MPPC circuit controls the inductor current to maintain VIN at the voltage on the MPPC pin. The MPPC pin
voltage is set by connecting a resistor between the MPPC
pin and GND, as shown in Figure 4. The MPPC voltage is
determined by the equation:
R1
VOUT = 1.004V •
+1
R2
VMPPC = 10µA • RMPPC
LDO Regulator Feedback Configuration
Two methods can be used to program the LDO output
voltage, as shown in Figure 3. A resistor divider connected
between the LDO and FBLDO pins can be used to program
the LDO output voltage. The equation for the LDO output
voltage is:
R3
VLDO = 1.004V •
+1
R4
Alternatively, the FBLDO pin can be connected directly to
GND. In this configuration, the LDO is internally set to a
nominal 2.2V output.
In photovoltaic cell applications, a diode can be used to
set the MPPC threshold so that it tracks the cell voltage
over temperature, as shown in Figure 5. The diode should
be thermally coupled to the photovoltaic cell to ensure
proper tracking. A resistor placed in series with the diode
can be used to adjust the DC set point to better match
the maximum power point of a particular source if the
selected diode forward voltage is too low. If the diode is
located far from the converter inputs, a capacitor may be
required to filter noise that may couple onto the MPPC
pin, as shown in Figure 5. This method can be extended
to stacked cell sources through use of multiple series
connected diodes.
VOUT
CFF1
R1
10µA
LTC3105
LTC3105
RMPPC
FB
MPPC
R2
3105 F02
3105 F04
Figure 4. MPPC Configuration
Figure 2. FB Configuration
LDO
R3
LTC3105
FBLDO
2.2V
LDO
RMPPC
LTC3105
FBLDO
+
VFWD
R4
–
3105 F03
Figure 3. FBLDO Configuration
10µA
MPPC
LTC3105
C6
10nF
3105 F05
Figure 5. MPPC Configuration with Temperature Adjustment
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11
LTC3105
APPLICATIONS INFORMATION
Industrial Current Loops
4mA TO 20mA
CURRENT LOOP
The low 250mV start-up and low voltage operation of the
LTC3105 allow it to be supplied by power from a diode
placed in an industrial sensor current loop, as shown
in Figure 6. In this application, a large input capacitor
is required due to the very low available supply current
(less than 4mA). The loop diode should be selected for a
minimum forward drop of 300mV. The MPPC pin voltage
should be set for a value approximately 50mV below the
minimum diode forward voltage.
VIN
+
VFWD
CIN
–
LTC3105
GND
RMPPC
MPPC
3105 F06
Figure 6. Current Loop Power Tap
TYPICAL APPLICATIONS
3.3V from a Single-Cell Photovoltaic Source with Temperature Tracking
L1**
10µH
VIN
+
CIN
10µF
–
R1
2.26M
LTC3105
PGOOD
MPPC
RMPPC OFF ON
9.09k
CMPPC
10nF
CAUX
1µF
LDO
SHDN
AUX
2.2V
VMPPC vs Temperature
COUT
10µF
R2
1M
FBLDO
GND
CLDO
4.7µF
* MRA4003T3
** COILCRAFT MSS5131-103MX
3105 TA02
MPPC Response to Input Source Current Step
0.7
VOUT = 2.8V
VMPPC = 0.4V
VFB = 0.94V
0.6
MPPC VOLTAGE (V)
VOUT
3.3V
FB
THERMALLY
COUPLED
D1*
SW
VOUT
0.5
0.4
0.3
INPUT VOLTAGE
50mV/DIV
0.2
INPUT CURRENT
25mA/DIV
0.1
OUTPUT CURRENT
5mA/DIV
0
–45 –30 –15
0 15 30 45 60
TEMPERATURE (°C)
75 90
3105 TA02a
0.38V
10mA
0.7mA
25µs/DIV
3105 TA02b
3105fb
12
For more information www.linear.com/LTC3105
LTC3105
TYPICAL APPLICATIONS
3.3V from Multiple Stacked-Cell Photovoltaic with Source Temperature Tracking
L1**
6.8µH
+
–
+
CIN
10µF
–
VIN
SW
R1
1.37M
LTC3105
RMPPC
4.99k
THERMALLY
COUPLED
FB
PGOOD
MPPC
OFF ON
D1*
VOUT
3.3V
VOUT
LDO
SHDN
CMPPC
10nF
AUX
D2*
2.2V
COUT
10µF
R2
604k
FBLDO
GND
CAUX
1µF
CLDO
4.7µF
3105 TA03
* MRA4003T3
** PANASONIC ELL-VEG6R8N
Thermoelectric Generator to 2.4V Super Capacitor Charger
L1**
10µH
∆T ≥ 10°C
+
VIN
TEG*
SW
VOUT
CIN
100µF
LTC3105
CFF
22pF
R1
1.10M
FB
OFF ON
RMPPC
30.1k
MPPC
PGOOD
SHDN
LDO
AUX
CAUX
1µF
2.2V
R2
787k
VOUT
2.4V
COUT
1µF
+
FBLDO
GND
CBULK
1F
2.5V
CLDO
4.7µF
3105 TA04
* MICROPELT MPG-D751
** COILCRAFT MSS5131-103MX
3105fb
For more information www.linear.com/LTC3105
13
LTC3105
TYPICAL APPLICATIONS
Industrial Sensor 4mA to 20mA Current Loop Power Tap
L1**
10µH
VIN
4mA TO 20mA
CURRENT LOOP
SW
VOUT
R1
2M
LTC3105
VFWD = 330mV
FB
CIN
470µF
D1*
PGOOD
280mV
LDO
MPPC
RMPPC
28k
OFF ON
AUX
* MBRS190T3
** COILCRAFT MSS5131-103MX
µP
+
10µF
VOUT, 3V
–
VDD
2.2V
CLDO
4.7µF
SHDN
CAUX
1µF
R2
1M
EN
RPG
499k
FBLDO
GND
3105 TA05
Transient Response to Load Pulse
with 4mA Loop Current
Start-Up VIN, VOUT , VLDO
VOUT VOLTAGE
500mV/DIV
VOUT VOLTAGE
250mV/DIV
LDO VOLTAGE
500mV/DIV
VIN VOLTAGE
50mV/DIV
0V
VIN VOLTAGE
200mV/DIV
LOAD CURRENT
2mA/DIV
100mV
2ms/DIV
50ms/DIV
3105 TA05a
3105 TA05b
Single-Cell Photovoltaic NiMH Trickle Charger
L1, 10µH
VIN
+
–
SW
VOUT
CIN
10µF
R1
1.02M
LTC3105
COUT
10µF
FB
OFF ON
MPPC
PGOOD
SHDN
LDO
R2
470k
CAUX
1µF
AUX
FBLDO
GND
+
NiMH
×2
1.8V
R3
1M
RMPPC
40.2k
VOUT
3.2V
+
R4
1.27M
CLDO
4.7µF
3105 TA06
3105fb
14
For more information www.linear.com/LTC3105
LTC3105
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LTC3105#packaging for the most recent package drawings.
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
0.70 ±0.05
3.55 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
3.00 ±0.10
(4 SIDES)
R = 0.125
TYP
6
0.40 ±0.10
10
1.65 ±0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.75 ±0.05
0.00 – 0.05
5
1
(DD) DFN REV C 0310
0.25 ±0.05
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
3105fb
For more information www.linear.com/LTC3105
15
LTC3105
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LTC3105#packaging for the most recent package drawings.
MS Package
12-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1668 Rev A)
0.889 ±0.127
(.035 ±.005)
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
4.039 ±0.102
(.159 ±.004)
(NOTE 3)
0.65
(.0256)
BSC
0.42 ±0.038
(.0165 ±.0015)
TYP
12 11 10 9 8 7
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
DETAIL “A”
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
0° – 6° TYP
0.406 ±0.076
(.016 ±.003)
REF
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
0.18
(.007)
SEATING
PLANE
1 2 3 4 5 6
1.10
(.043)
MAX
0.22 – 0.38
(.009 – .015)
TYP
0.650
(.0256)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.86
(.034)
REF
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS12) 0213 REV A
3105fb
16
For more information www.linear.com/LTC3105
LTC3105
REVISION HISTORY
REV
DATE
DESCRIPTION
A
01/11
Added (Note 5) notation to Input Start-Up Voltage conditions.
3
Added Note 5.
3
Updated Start-Up Mode Operation section.
8
B
11/15
PAGE NUMBER
VOUT range changed.
3
Changed G09 curve.
4
Changed feedback description.
6
Changed VOUT range.
7
3105fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
For more
information
www.linear.com/LTC3105
17
LTC3105
TYPICAL APPLICATION
Single-Cell Powered Remote Wireless Sensor
L1*
10µH
VIN
+
SW
CIN
10µF
–
VOUT
3.3V
VOUT
R1
2.32M
LTC3105
FB
MPPC
RMPPC
40.2k
COUT
100µF
R2
1.02M
XMTR
I/O
OFF ON
SHDN
LDO
AUX
2N7000
EN
PGOOD
CAUX
1µF
2.2V
FBLDO
GND
µC
RPG
499k
VDD
CLDO
4.7µF
* COILCRAFT MSS5131-103MX
A/D
SENSOR
GPIO
GND
3105 TA07
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LTC3106
300mA Low Voltage Buck-Boost Converter with
PowerPath™ and 1.6μA Quiescent Current
300mV ≤ VIN ≤ 5.1V; Selectable Output Voltages Primary or Rechargeable Backup
Batteries, MPPC, 3mm × 4mm QFN-20, TSSOP-20E Packages, Solar and TEG
LTC3330
Dual Input Nanopower Buck-Boost DC/DC with
Energy Harvesting Battery Life Extender, Input
Prioritizer and Up to 50mA of IOUT
3V ≤ VIN ≤ 19V for EH; 1.8V ≤ VIN ≤ 5V for Battery Full-Wave Bridge Rectifier,
Super Cap Balancer 5mm × 5mm QFN-32, Solar and Vibration
LTC3331
Dual Input Nanopower Buck-Boost DC/DC with
Energy Harvesting 10mA Shunt Battery Charger
Input Prioritizer and Up to 50mA of IOUT
3V ≤ VIN ≤ 19V for EH; 1.8V ≤ VIN ≤ 4.2V for Battery Full-Wave Bridge Rectifier,
Super Cap Balancer Programmable Float Voltages, 5mm × 5mm QFN-32, Solar
and Vibration
LTC3109
Auto-Polarity, Ultralow Voltage Step-Up Converter
and Power Manager
±0.03V ≤ VIN ≤ ±0.50V, Selectable VOUT of 2.35V, 3.3V, 4.1V or 5V Uses Compact
Step-Up Transformers, IQ = 7μA; 4mm × 4mm QFN-20 SSOP-20 Packages, TEG
and Thermopiles
LTC3108/
LTC3108-1
Ultralow Voltage Step-Up Converter and Power
Manager
0.03V ≤ VIN ≤ 0.50V, Selectable VOUT of 2.5V, 3V, 3.7V or 4.5V Uses Compact
Step-Up Transformers, IQ = 7μA; 3mm × 4mm DFN-12 SSOP-16 Packages, TEG
and Thermopiles
LTC4070
Li-Ion/Polymer Shunt Battery Charger System
450nA IQ; 1% Float Voltage Accuracy; 50mA Shunt Current 4.0V/4.1V/4.2V,
DFN-8 and MSOP-8E Packages
LTC4071
Li-Ion/Polymer Shunt Battery Charger System with
Low Battery Disconnect
550nA IQ; 1% Float Voltage Accuracy;
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