LTC3225-1 [Linear]
400mA Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up; 400毫安升压型DC / DC转换器，最大功率点控制和250mV启动
| 型号： | LTC3225-1 |
| 厂家： | 
Linear |
| 描述： | 400mA Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up |
| 文件： | 总18页 (文件大小：1913K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC3105
400mA Step-Up DC/DC
Converter with Maximum Power
Point Control and 250mV Start-Up
FEATURES
DESCRIPTION
TheLTC®3105isahighefficiencystep-upDC/DCconverter
that can operate from input voltages as low as 225mV. A
250mVstart-upcapabilityandintegratedmaximumpower
pointcontroller(MPPC)enableoperationdirectlyfromlow
voltage,highimpedancealternativepowersourcessuchas
photovoltaic cells, TEGs (thermoelectric generators) and
fuelcells.AuserprogrammableMPPCsetpointmaximizes
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
Low Start-Up Voltage: 250mV
n
Maximum Power Point Control
n
Wide V Range: 225mV to 5V
IN
n
Auxiliary 6mA LDO Regulator
Burst Mode® Operation: I = 24µA
n
Q
n
Output Disconnect and Inrush Current Limiting
n
V > V
Operation
IN
OUT
n
n
n
n
n
Antiringing Control
Soft Start
Automatic Power Adjust
Power Good Indicator
10-Lead 3mm × 3mm × 0.75mm DFN and 12-Lead
MSOP Packages
The AUX powered 6mA LDO provides a regulated rail for
external microcontrollers and sensors while the main
output is charging. In shutdown, I is reduced to 10µA
and integrated thermal shutdown offers protection from
overtemperature faults. The LTC3105 is offered in 10-lead
3mm×3mm×0.75mmDFNand12-leadMSOPpackages.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Q
APPLICATIONS
n
Solar Powered Battery/Supercapacitor Chargers
n
Energy Harvesting
n
Remote Industrial Sensors
Low Power Wireless Transmitters
Cell Phone, MP3, PMP and GPS Accessory Chargers
n
n
TYPICAL APPLICATION
Single Photovoltaic Cell Li-Ion Trickle Charger
Output Current vs Input Voltage
80
10µH
MPPC DISABLED
70
225mV TO 5V
V
= 3.3V
OUT
V
SW
OUT
IN
60
50
40
30
20
10
0
+
–
V
OUT
PHOTOVOLTAIC
CELL
V
4.1V
10µF
V
= 4.2V
OUT
LTC3105
1020k
332k
V
= 5V
FB
OUT
Li-Ion
MPPC
SHDN
AUX
PGOOD
LDO
OFF
ON
2.2V
10µF
40.2k
FBLDO
GND
4.7µF
1µF
0.2 0.3
0.5 0.6 0.7 0.8 0.9 1.0
INPUT VOLTAGE (V)
0.4
3105 TA01a
3105 TA01b
3105fa
1
LTC3105
ABSOLUTE MAXIMUM RATINGS
SW Voltage
(Note 1)
Maximum Junction Temperature (Note 4) ............ 125°C
Storage Temperature.............................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec.)
DC............................................................ –0.3V to 6V
Pulsed (<100ns)...........................................–1V to 7V
Voltage, All Other Pins ................................. –0.3V to 6V
Operating Junction Temperature
MS Package......................................................300°C
Range (Note 2).........................................–40°C to 85°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
FB
LDO
1
2
3
4
5
10 AUX
1
2
3
4
5
6
FB
LDO
FBLDO
SHDN
MPPC
GND
12 AUX
11
10 PGOOD
9
8
7
6
V
OUT
V
OUT
11
GND
FBLDO
SHDN
MPPC
PGOOD
SW
9
8
7
SW
V
IN
V
IN
GND
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
MS PACKAGE
12-LEAD PLASTIC MSOP
T
= 125°C, θ = 130°C/W, θ = 21°C/W
JA JC
T
= 125°C, θ = 43°C/W, θ = 3°C/W
JMAX
JMAX
JA
JC
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3105EDD#PBF
LTC3105EMS#PBF
TAPE AND REEL
PART MARKING
LFQC
PACKAGE DESCRIPTION
TEMPERATURE RANGE
–40°C to 85°C
LTC3105EDD#TRPBF
LTC3105EMS#TRPBF
10-Lead (3mm × 3mm) Plastic DFN
12-Lead Plastic MSOP
3105
–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/
3105fa
2
LTC3105
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VAUX = VOUT = 3.3V, VLDO = 2.2V, VIN = 0.6V, unless
otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Step-Up Converter
Input Operating Voltage
Input Start-Up Voltage
l
l
0.225
5
V
(Note 5)
J
0.25
0.4
0.36
V
V
T = 0°C to 85°C (Note 5)
l
l
Output Voltage Adjust Range
Feedback Voltage (FB Pin)
1.5
5.25
V
V
0.984
1.004
24
1.024
V
OUT
V
OUT
I in Operation
V = 1.10V
FB
µA
µA
µA
V
Q
I in Shutdown
Q
SHDN = 0V
10
MPPC Pin Output Current
V
= 0.6V
9.72
1.1
10
10.28
MPPC
l
l
SHDN Input Logic High Voltage
SHDN Input Logic Low Voltage
N-Channel SW Pin Leakage Current
P-Channel SW Pin Leakage Current
N-Channel On-Resistance: SW to GND
0.3
10
10
V
V
V
= V = 5V, V = 0V
SHDN
1
1
µA
µA
Ω
Ω
A
IN
SW
= V = 0V, V
= V
= 5.25V
AUX
IN
SW
OUT
0.5
0.5
0.5
0.35
90
P-Channel On-Resistance: SW to V
Peak Current Limit
OUT
V
V
V
= 0.90V, V
= 0.90V, V
= 0.4V (Note 3)
= 0.4V (Note 3)
0.4
0.275
85
FB
MPPC
MPPC
Valley Current Limit
A
FB
PGOOD Threshold (% of Feedback Voltage)
LDO Regulator
Falling
95
%
OUT
l
l
l
LDO Output Adjust Range
LDO Output Voltage
External Feedback Network, V
> V
1.4
5
V
V
AUX
LDO
V
FBLDO
= 0V
2.148
0.984
2.2
1.004
0.40
0.15
105
12
2.236
1.024
Feedback Voltage (FBLDO Pin)
Load Regulation
External Feedback Network
V
I
= 1mA to 6mA
= 2.5V to 5V
%
LDO
Line Regulation
V
%
AUX
LDO
Dropout Voltage
I
= 6mA, V
= V
= 2.2V
mV
mA
µA
OUT
AUX
l
LDO Current Limit
V
0.5V Below Regulation Voltage
6
LDO
LDO Reverse-Blocking Leakage Current
V
IN
= V
= V
= 0V, V = 0V
SHDN
1
AUX
OUT
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 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.
Note 2: The LTC3105 is tested under pulsed load conditions such that
T
≈
T . The LTC3105E is guaranteed to meet specifications from
J
A
0°C to 85°C junction temperature. Specifications over the –40°C to 85°C
operating junction temperature range are assured by design, character-
ization 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.
3105fa
3
LTC3105
TA = 25°C, VAUX = VOUT = 3.3V, VLDO = 2.2V,
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 0.6V, unless otherwise noted.
Minimum Input Start-Up Voltage
vs Temperature
Shutdown Thresholds
vs Input Voltage
IC Enable Delay vs Input Voltage
120
340
320
300
280
260
240
220
200
1000
900
800
700
600
500
400
300
200
100
0
IC ENABLE
IC DISABLE
100
80
60
40
1.25
2.25
SUPPLY VOLTAGE, V OR V
AUX
4.25
5.25
1.25
2.25
4.25
5.25
3.25
3.25
–45 –30 –15
0
15 30 45 60 75 90
SUPPLY VOLTAGE, V OR V
(V)
(V)
TEMPERATURE (°C)
IN
AUX
IN
3105 G01
3105 G02
3105 G03
MPPC Current Variation
vs Temperature
LDO Soft-Start Duration
vs LDO Load
2.5
2.0
1.5
1.0
0.5
0
1.25
1.20
1.15
1.10
1.05
1.00
0.95
–0.5
–1.0
–1.5
–45 –30 –15
0
15 30 45 60 75 90
1
3
4
5
6
2
TEMPERATURE (°C)
LDO LOAD CURRENT (mA)
3105 G05
3105 G06
VOUT IQ vs Temperature
During Shutdown
VIN for Synchronous Operation
22
20
18
16
14
12
10
8
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
SHDN = 0V
NONSYNCHRONOUS
OPERATION
SYNCHRONOUS
OPERATION
6
4
1.5 2.0 2.5
4.0 4.5 5.0 5.5
–45 –30 –15
0
15 30 45 60 75 90
3.0 3.5
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
3105 G07
3105 G09
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4
LTC3105
TA = 25°C, VAUX = VOUT = 3.3V, VLDO = 2.2V,
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 0.6V, unless otherwise noted.
Exiting MPPC Control on
Input Voltage Step
IPEAK and IVALLEY Current Limit
Change vs Temperature
Efficiency vs VIN
1.0
0.5
100
90
80
70
60
50
40
V
= 400mV
MPPC
V
I
= 3V
V
VOLTAGE
OUT
LOAD
IN
I
PEAK
= 10mA
200mV/DIV
LDO = 2.2V
0
I
VALLEY
INDUCTOR
CURRENT
100mA/DIV
–0.5
–1.0
–1.5
–2.0
–2.5
MPPC VOLTAGE
200mV/DIV
15µs/DIV
0.25
2.25
3.25
4.25
5.25
–45 –30 –15
0
15 30 45 60 75 90
1.25
3105 G10
INPUT VOLTAGE (V)
TEMPERATURE (°C)
3105 G11
3105 G12
Efficiency vs Output Current and
Power Loss, VOUT = 3.3V
Input and Output Burst Ripple
90
80
70
60
50
40
30
20
10
0
1000
100
10
V
V
V
= 0.6V
= 0.8V
= 1V
V
C
= 0.6V
= 470µF
V
I
= 3.3V
= 15mA
= 10µF
IN
IN
IN
IN
IN
OUT
OUT
OUT
EFFICIENCY
C
OUTPUT
VOLTAGE
50mV/DIV
SW CURRENT
200mA/DIV
POWER LOSS
1
INPUT
VOLTAGE
5mV/DIV
0.1
1
10
100
0.01
0.1
50µs/DIV
3105 G13
OUTPUT CURRENT (mA)
3105 G14
Efficiency vs Output Current and
Power Loss, VOUT = 5V
No-Load Input Current
vs Input Voltage
100
90
80
70
60
50
40
30
20
1000
800
700
600
500
400
300
200
100
0
V
= 3.3V
V
IN
V
IN
V
IN
= 3V
OUT
= 2V
= 1.5V
100
10
1
EFFICIENCY
POWER LOSS
0.1
1
10
100
0.01
0.1
0.2
0.6
0.8
1.0
1.2
0.4
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
3105 G15
3105 G16
3105fa
5
LTC3105
PIN FUNCTIONS (DFN/MSOP)
FB (Pin 1/Pin 1): Step-Up Converter Feedback Input. Con-
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.
nect the V
resistor divider tap to this input. The output
OUT
voltage can be adjusted between 1.5V and 5.25V.
LDO(Pin2/Pin2):LDORegulatorOutput.Connecta4.7µF
or larger capacitor between LDO and GND.
SW(Pin7/Pin9):SwitchPin.Connectaninductorbetween
SW and V . PCB trace lengths should be as short as pos-
IN
FBLDO (Pin 3/Pin 3): LDO Feedback Input. Connect the
LDO resistive divider tab to this input. Alternatively, con-
necting FBLDO directly to GND will configure the LDO
output voltage to be internally set at 2.2V (nominal).
sible to reduce EMI. While the converter is sleeping or is
in shutdown, the internal antiringing switch connects the
SW pin to the V pin in order to minimize EMI.
IN
PGOOD (Pin 8/Pin 10): Power Good Indicator. This is an
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
anopen-drainoropen-collectorpull-downandfloateduntil
the converter has entered normal operation. Excessive
loadingonthispinmaycauseafailuretocompletestart-up.
open-drain output. The pull-down is disabled when V
OUT
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.
V
OUT
(Pin9/Pin11):Step-UpConverterOutput. Thisisthe
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
SHDN = Low: IC Disabled
SHDN = High: IC Enabled
V
pin to the output filter capacitor should be as short
OUT
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.
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.
V
(Pin 6/Pin 8): Input Supply. Connect a decoupling
IN
AUXandV
exceeds V
areinternallyconnectedtogetheronceV
OUT
AUX
OUT
capacitor between this pin and GND. The PCB trace length
.
from the V pin to the decoupling capacitor should be as
IN
short and wide as possible. When used with high imped-
ance sources such as photovoltaic cells, this pin should
have a 10µF or larger decoupling capacitor.
3105fa
6
LTC3105
BLOCK DIAGRAM (Pin Numbers for DFN Package Only)
L1
10µH
7
SHUTDOWN
SLEEP
SW
WELL
CONTROL
OR
AUX
10
C
AUX
1µF
SHORT
CONTROL
V
V
OUT
1.5V TO
5.25V
IN
LOW VOLTAGE
START-UP
225mV
TO 5V
6
9
2
CURRENT
ADJUST
C
OUT
C
IN
10µF
10µF
LDO
V
AUX
SHUTDOWN
V
CC
C
LDO
4.7µF
+
+
–
–
10µA
MPPC
PEAK CURRENT
LIMIT
5
4
–
+
g
m
V
IN
SHUTDOWN
SLEEP
R
MPPC
V
CC
2M
–
+
VALLEY CURRENT LIMIT
USER SHUTDOWN
LOGIC
R3
R4
R1
R2
SHDN
FBLDO
BURST
1.004V
3
CONTROL
FB
1
8
–
+
PGOOD
V
IN
1.004V
FB
–
+
V
V
AUX
CC
0.9V
EXPOSED PAD
SLEEP
11
3105 BD
3105fa
7
LTC3105
OPERATION
Introduction
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
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.Thispartoperatesoveraverywiderangeofinput
voltages from 225mV to 5V. Its Burst Mode architecture
and low 24µA quiescent current optimize efficiency in low
power applications.
AUX and V
is enabled.
OUT
When the SHDN pin is released, the LTC3105 is enabled
and begins switching after a short delay. When either V
IN
or V
is above 1.4V, this delay will typically range be-
AUX
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
adjustedwithproprietarytechniquestomaintainoperation
at levels that maximize power extraction from the source.
tween 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
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.
V
AUX
hasreachedapproximately1.4V,theconverterleaves
start-up mode and enters normal operation. Maximum
powerpointcontrolisnotenabledduringstart-up,however,
the currents are internally limited to sufficiently low levels
to allow start-up from weak input sources.
Synchronous rectification provides high efficiency opera-
tionwhileeliminatingtheneedforexternalSchottkydiodes.
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
Whiletheconverterisinstart-upmode, theinternalswitch
between AUX and V
remains disabled and the LDO
OUT
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
fromverylowimpedance,lowinputvoltagesources,itmay
be necessary to add several hundred milliohms of series
input resistance to allow for proper low voltage start-up.
disconnect isolates V
from V while in shutdown.
OUT
IN
V > V
Operation
IN
OUT
Normal Operation
The LTC3105 includes the ability to seamlessly maintain
regulation if V becomes equal to or greater than V
.
OUT
When either V or V
is greater than 1.4V typical, the
IN
IN
AUX
With V greater than or equal to V , the synchro-
converter will enter normal operation.
IN
OUT
nous rectifiers are disabled which may result in reduced
efficiency.
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 V
OUT
Shutdown Control
pin. V
is maintained at a level sufficient to ensure the
AUX
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
LDO remains in regulation. If V
becomes higher than
AUX
required to maintain LDO regulation, charge is transferred
from the AUX output to the V output. If V falls too
low, current is redirected to the AUX output instead of
being used to charge the V output. Once V rises
OUT
AUX
OUT
OUT
3105fa
8
LTC3105
OPERATION
TIME
V
V
LDO
V
OUT
AUX
1.4V
TIME
V
IN
OUT
REGULATION
LDO IN
REGULATION
V
OUT
= V
AUX
V
SYNCHRONOUS
OUT
RECTIFIER ENABLED
START-UP MODE NORMAL OPERATION
3105 F01
Figure 1. Typical Converter Start-Up Sequence
above V , an internal switch is enabled to connect the
When V
reaches the regulation point, the N- and P-
OUT
AUX
two outputs together.
channel MOSFETs connected to the SW pin are disabled
and the converter enters sleep.
IfV isgreaterthanthevoltageonthedrivenoutput(V
IN
OUT
or V ), or the driven output is less than 1.2V (typical),
AUX
Auxiliary LDO
the synchronous rectifiers are disabled. With the synchro-
nous 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.
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 pro-
When the output voltage is greater than the input voltage
andgreaterthan1.2V,thesynchronousrectifierisenabled.
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
MOSFETturnsoffandtheP-channelMOSFETbetweenSW
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.
grammed V
.
OUT
3105fa
9
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 V
risen above the LDO voltage.
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 in-
creased 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.
has
AUX
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
PGOOD Operation
from dropping below the MPPC threshold. When V is
IN
greater than the MPPC voltage, the inductor current is
The power good output is used to indicate that V
is
OUT
increased until V is pulled down to the MPPC set point.
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
IN
If V is less than the MPPC voltage, the inductor current
IN
is reduced until V rises to the MPPC set point.
IN
Automatic Power Adjust
value. PGOOD remains asserted until V
drops below
OUT
90% of its regulation value at which point PGOOD will
pull low.
The LTC3105 incorporates a feature that maximizes ef-
ficiency at light load while providing increased power
APPLICATIONS INFORMATION
Component Selection
should be large enough to allow the converter to complete
start-up mode using the energy stored in the input ca-
pacitor. When using bulk input capacitors that have high
ESR, a small valued parallel ceramic capacitor should be
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
placed between V and GND as close to the converter
IN
pins as possible.
A 1µF ceramic capacitor should be connected between
AUX and GND. Larger capacitors should be avoided to
minimizestart-uptime.AlowESRoutputcapacitorshould
is relatively high (V > 0.8V), smaller inductors may be
IN
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,efficiencywillbereducedandtheminimumoperating
voltage will increase.
be connected between V
and GND. The main output
OUT
capacitor should be 10µF or larger. The main output can
also be used to charge energy storage devices including
tantalumcapacitors, supercapacitorsandbatteries. 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.
Inputcapacitorselectionishighlyimportantinlowvoltage,
high source resistance systems. For general applications,
a 10µF ceramic capacitor is recommended between V
IN
andGND. Forhighimpedancesources, theinputcapacitor
3105fa
10
LTC3105
APPLICATIONS INFORMATION
Step-Up Converter Feedback Configuration
MPPC Threshold Configuration
AresistordividerconnectedbetweentheV
programs the step-up converter output voltage, as shown
in Figure 2. An optional 22pF feedforward capacitor, C
andFBpins
The MPPC circuit controls the inductor current to main-
OUT
tain V at the voltage on the MPPC pin. The MPPC pin
IN
,
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:
FF1
can be used to reduce output ripple and improve load
transient response. The equation for V is:
OUT
V
MPPC
= 10µA • R
MPPC
R1
R2
VOUT = 1.004V •
+ 1
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.
LDO Regulator Feedback Configuration
Two methods can be used to program the LDO output
voltage, asshowninFigure3. Aresistordividerconnected
between the LDO and FBLDO pins can be used to program
the LDO output voltage. The equation for the LDO output
voltage is:
R3
R4
VLDO = 1.004V •
+ 1
Alternatively, the FBLDO pin can be connected directly to
GND. In this configuration, the LDO is internally set to a
nominal 2.2V output.
V
OUT
MPPC
10µA
C
R1
R2
FF1
LTC3105
LTC3105
R
MPPC
FB
3105 F02
3105 F04
Figure 2. FB Configuration
Figure 4. MPPC Configuration
2.2V
MPPC
10µA
LDO
LDO
R
MPPC
R3
R4
LTC3105
FBLDO
LTC3105
FBLDO
LTC3105
+
C6
10nF
V
FWD
–
3105 F03
3105 F05
Figure 5. MPPC Configuration with Temperature Adjustment
Figure 3. FBLDO Configuration
3105fa
11
LTC3105
APPLICATIONS INFORMATION
Industrial Current Loops
4mA TO 20mA
V
IN
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.
CURRENT LOOP
+
V
C
IN
FWD
LTC3105
–
GND
R
MPPC
MPPC
3105 F06
Figure 6. Current Loop Power Tap
TYPICAL APPLICATIONS
3.3V from a Single-Cell Photovoltaic Source with Temperature Tracking
L1**
10µH
V
SW
OUT
IN
+
–
V
OUT
V
C
IN
3.3V
10µF
R1
2.26M
LTC3105
FB
C
THERMALLY
COUPLED
OUT
10µF
MPPC
SHDN
AUX
PGOOD
LDO
R2
1M
R
OFF
MPPC
ON
2.2V
9.09k
FBLDO
C
MPPC
D1*
10nF
GND
C
LDO
C
1µF
AUX
4.7µF
3105 TA02
* MRA4003T3
** COILCRAFT MSS5131-103MX
VMPPC vs Temperature
MPPC Response to Input Source Current Step
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
V
V
V
= 2.8V
MPPC
= 0.94V
OUT
= 0.4V
FB
0.38V
INPUT VOLTAGE
50mV/DIV
10mA
0.7mA
INPUT CURRENT
25mA/DIV
OUTPUT CURRENT
5mA/DIV
–45 –30 –15
0
15 30 45 60 75 90
25µs/DIV
TEMPERATURE (°C)
3105 TA02a
3105 TA02b
3105fa
12
LTC3105
TYPICAL APPLICATIONS
3.3V from Multiple Stacked-Cell Photovoltaic with Source Temperature Tracking
L1**
6.8µH
+
–
+
V
SW
OUT
IN
V
C
OUT
IN
V
3.3V
10µF
–
R1
LTC3105
1.37M
R
MPPC
FB
THERMALLY
COUPLED
C
4.99k
OUT
10µF
MPPC
SHDN
AUX
PGOOD
LDO
R2
604k
OFF
ON
2.2V
D1*
D2*
C
10nF
MPPC
FBLDO
GND
C
LDO
C
1µF
AUX
4.7µF
3105 TA03
* MRA4003T3
** PANASONIC ELL-VEG6R8N
Thermoelectric Generator to 2.4V Super Capacitor Charger
L1**
10µH
∆T ≥ 10°C
+
V
SW
OUT
IN
TEG*
V
OUT
V
C
IN
2.4V
100µF
C
R1
1.10M
FF
LTC3105
22pF
C
OUT
FB
1µF
R2
787k
MPPC
SHDN
AUX
PGOOD
LDO
+
C
BULK
1F
OFF
ON
2.2V
2.5V
FBLDO
R
MPPC
30.1k
GND
C
LDO
C
1µF
AUX
4.7µF
3105 TA04
* MICROPELT MPG-D751
** COILCRAFT MSS5131-103MX
3105fa
13
LTC3105
TYPICAL APPLICATIONS
Industrial Sensor 4mA to 20mA Current Loop Power Tap
L1**
10µH
V
SW
OUT
IN
V
R1
2M
LTC3105
V
= 330mV
FWD
4mA TO 20mA
CURRENT LOOP
FB
R2
1M
C
IN
PGOOD
EN
µP
470µF
R
+
PG
D1*
499k
10µF
V
, 3V
OUT
280mV
MPPC
LDO
V
DD
–
2.2V
OFF
C
ON
SHDN
LDO
R
4.7µF
MPPC
AUX
FBLDO
28k
C
AUX
GND
1µF
* MBRS190T3
** COILCRAFT MSS5131-103MX
3105 TA05
Transient Response to Load Pulse
with 4mA Loop Current
Start-Up VIN, VOUT, VLDO
V
VOLTAGE
OUT
V
VOLTAGE
OUT
500mV/DIV
250mV/DIV
LDO VOLTAGE
500mV/DIV
V
VOLTAGE
IN
50mV/DIV
0V
V
VOLTAGE
IN
200mV/DIV
LOAD CURRENT
2mA/DIV
100mV
50ms/DIV
2ms/DIV
3105 TA05b
3105 TA05a
Single-Cell Photovoltaic NiMH Trickle Charger
L1, 10µH
V
SW
OUT
IN
V
OUT
+
–
V
C
IN
3.2V
+
+
10µF
R1
C
OUT
LTC3105
1.02M
NiMH
× 2
10µF
FB
R2
470k
MPPC
PGOOD
OFF
ON
SHDN
LDO
1.8V
R3
R
MPPC
1M
40.2k
C
LDO
AUX
FBLDO
4.7µF
C
AUX
GND
R4
1.27M
1µF
3105 TA06
3105fa
14
LTC3105
PACKAGE DESCRIPTION
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
0.70 ±0.05
3.55 ±0.05
2.15 ±0.05 (2 SIDES)
1.65 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.125
0.40 ± 0.10
TYP
6
10
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
PIN 1
TOP MARK
(SEE NOTE 6)
0.35 × 45°
CHAMFER
(DD) DFN REV C 0310
5
1
0.25 ± 0.05
0.50 BSC
0.75 ±0.05
0.200 REF
2.38 ±0.10
(2 SIDES)
0.00 – 0.05
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
3105fa
15
LTC3105
PACKAGE DESCRIPTION
MS Package
12-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1668 Rev Ø)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
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
0.406 ± 0.076
(.016 ± .003)
REF
12 11 10 9 8 7
RECOMMENDED SOLDER PAD LAYOUT
DETAIL “A”
0° – 6° TYP
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
4.90 ± 0.152
(.193 ± .006)
0.254
(.010)
GAUGE PLANE
0.53 ± 0.152
(.021 ± .006)
1
2 3 4 5 6
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
0.1016 ± 0.0508
(.004 ± .002)
MSOP (MS12) 1107 REV Ø
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
3105fa
16
LTC3105
REVISION HISTORY
REV
DATE
DESCRIPTION
PAGE NUMBER
A
02/11 Added (Note 5) notation to Input Start-Up Voltage conditions
Added Note 5
3
3
8
Updated Start-Up Mode Operation section
3105fa
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
17
LTC3105
TYPICAL APPLICATION
Single-Cell Powered Remote Wireless Sensor
L1*
10µH
V
SW
OUT
IN
+
–
V
OUT
C
IN
V
3.3V
10µF
R1
2.32M
LTC3105
C
OUT
100µF
XMTR
I/O
MPPC
FB
R2
1.02M
R
MPPC
40.2k
SENSOR
PGOOD
LDO
EN
A/D
OFF
ON
µC
R
PG
SHDN
2.2V
499k
AUX
FBLDO
V
GPIO
GND
DD
2N7000
GND
C
LDO
C
AUX
4.7µF
1µF
3105 TA07
* COILCRAFT MSS5131-103MX
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
V : 0.02V to 1V; V
LTC3108/LTC3108-1
Ultralow Voltage Step-Up Converter and Power
Manager
= 2.2V, 2.35V, 3.3V, 4.1V, 5V; I = 6μA; 4mm × 3mm
OUT Q
IN
DFN-12, SSOP-16 Packages; LTC3108-1 V
= 2.2V, 2.5V, 3V, 3.7V, 4.5V
OUT
LTC3109
Auto-Polarity, Ultralow Voltage Step-Up
Converter and Power Manager
|V |: 0.03V to 1V; V
= 2.2V, 2.35V, 3.3V, 4.1V, 5V; I = 7μA; 4mm × 4mm
OUT Q
IN
QFN-20, SSOP-20 Packages
LTC4070
LTC4071
Li-Ion/Polymer Shunt Battery Charger System
450nA I ; 1% Float Voltage Accuracy; 50mA Shunt Current 4.0V/4.1V/4.2V
Q
Li-Ion/Polymer Shunt Battery Charger System
with Low Battery Disconnect
550nA I ; 1% Float Voltage Accuracy; <10nA Low Battery Disconnect;
Q
4.0V/4.1V/4.2V; 8-Lead 2mm × 3mm DFN and MSOP Packages
LTC3588-1/LTC3588-2
LTC3388-1/LTC3388-3
Piezoelectric Energy Harvesting Power Supply
< 1µA I in Regulation; 2.7V to 20V Input Range; Integrated Bridge Rectifier
Q
20V High Efficiency Nanopower Step-Down
Regulator
860nA I in Sleep; 2.7V to 20V Input; V : 1.2V to 5V; Enable and
Q
OUT
Standby Pins
LTC3225/LTC3225-1
150mA Super Capacitor Charger
Programmable Charge Current Up to 150mA; Constant-Frequency Charging
of Two Series Supercapacitors; No Inductors; 2mm × 3mm DFN Package
LTC3525-3/LTC3525-3.3/ 400mA Micropower Synchronous Step-Up
95% Efficiency; V : 1V to 4.5V; V
SD
= 3V, 3.3V or 5V; I = 7μA;
OUT Q
IN
LTC3525-5/LTC3525L-3
DC/DC Converter with Output Disconnect
I
< 1μA; SC70 Package; LTC3525L-3 V : 0.7V to 4.5V
IN
LTC3526L/LTC3526L-2/
550mA, 1MHz/2MHz Synchronous Boost
95% Efficiency; V : 0.7V to 5.5V; V
SD
= 5.25V; I = 9μA;
Q
IN
OUT(MAX)
LTC3526LB/LTC3526LB-2 Converter
I
< 1μA; 2mm × 2mm DFN Package
LTC3527
Dual 2.2MHz 800mA/400mA Synchronous Step- V : 0.5V to 5V; V
: 1.6V to 5.25V; I = 12μA; I < 1μA;
IN
OUT
Q
SD
Up DC/DC Converters
3mm × 3mm QFN Package
LTC3528/LTC3528-2/
LTC3528B/LTC3528B-2
1A (I ), 1MHz/2MHz Synchronous Step-Up
94% Efficiency; V : 0.7V to 5.5V; V
SD
= 5.25V; I = 12μA;
OUT(MAX) Q
SW
IN
DC/DC Converter with Output Disconnect
I
< 1μA; 2mm × 3mm DFN-8 Package
LTC3537
2.2MHz, 600mA Synchronous Step-Up DC/DC
Converter and 100mA LDO
V : 0.68V to 5V; V
IN
: 1.5V to 5.25V; 3mm × 3mm QFN Package
OUT
LTC3539/LTC3539-2
2A (I ), 1MHz/2MHz Synchronous Step-Up
94% Efficiency; V : 0.7V to 5V; V
SD
= 5.25V; I = 10μA;
OUT(MAX) Q
SW
IN
DC/DC Converter with Output Disconnect
I
< 1μA; 2mm × 3mm DFN Package
3105fa
LT 0211 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
18
●
●
LINEAR TECHNOLOGY CORPORATION 2010
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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