LT1673 [Linear Systems]
Auto-Polarity, Ultralow Voltage Step-Up Converter and Power Manager; 自动极性,超低电压,升压型转换器和电源管理器型号: | LT1673 |
厂家: | Linear Systems |
描述: | Auto-Polarity, Ultralow Voltage Step-Up Converter and Power Manager |
文件: | 总24页 (文件大小:235K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC3109
Auto-Polarity, Ultralow
Voltage Step-Up Converter
and Power Manager
DESCRIPTION
TheLTC®3109isahighlyintegratedDC/DCconverterideal
for harvesting surplus energy from extremely low input
voltage sources such as TEGs (thermoelectric genera-
tors) and thermopiles. Its unique, proprietary autopolarity
topology* allows it to operate from input voltages as low
as 30mV, regardless of polarity.
FEATURES
n
Operates from Inputs as Low as ±±3mV
n
Less Than ±ꢀ1C ꢁeeꢂeꢂ ꢃAross TEG to ꢄarvest
Energy
n
Proprietary ꢃuto-Polarity ꢃrAhiteAture
n
Complete Energy ꢄarvesting Power Management
System
– SeleAtable V
of 2.±5V, ±.±V, 4.ꢀV or 5V
OUT
Using two compact step-up transformers and external
energy storage elements, the LTC3109 provides a com-
plete power management solution for wireless sensing
and data acquisition. The 2.2V LDO can power an external
microprocessor,whilethemainoutputcanbeprogrammed
to one of four fixed voltages. The power good indicator
signals that the main output is within regulation. A second
output can be enabled by the host. A storage capacitor (or
battery) can also be charged to provide power when the
input voltage source is unavailable. Extremely low quies-
cent current and high efficiency maximizes the harvested
energy available for the application.
– 2.2V, 5mꢃ LDO
– LogiA-Controlleꢂ Output
– Energy Storage Capability for Operation During
Power Interruption
n
n
n
Power Gooꢂ InꢂiAator
Uses Compact Step-up Transformers
Small, 20-lead (4mm × 4mm) QFN Package or
20-Lead SSOP
APPLICATIONS
n
Remote Sensor and Radio Power
The LTC3109 is available in a small, thermally enhanced
20-lead (4mm × 4mm) QFN package and a 20-lead SSOP
package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
*Patent pending.
n
HVAC Systems
n
Automatic Metering
n
Building Automation
n
Predictive Maintenance
n
Industrial Wireless Sensing
TYPICAL APPLICATION
TEG
(THERMOELECTRIC GENERATOR)
1nF
VOUT Current vs TEG Voltage
30mV TO 500mV
1:100
C1A
V
OPTIONAL SWITCHED OUTPUT FOR SENSORS
OUT2
•
•
900
800
700
600
500
400
300
200
100
1:100 TRANSFORMERS
C1A = C1B = 1nF
470pF
3.3V
2.2V
C2A
V
47μF
OUT
V
OUT
= 3.3V
+
470μF
SWA
VLDO
2.2μF
V
LOW POWER
RADIO
INA
1nF
LTC3109
1:100
C1B
•
•
SENSOR(S)
μP
470pF
C2B
PG00D
SWB
V
OUT2_EN
V
INB
5.25V
VS1
VS2
VAUX
VSTORE
VAUX
0
+
–300 –200 –100
0
300
100
200
1μF
C
STORE
GND
V
(mV)
TEG
3109 TA01a
3109 TA01b
3109fa
1
LTC3109
ABSOLUTE MAXIMUM RATINGS (ꢁote ꢀ)
SWA, SWB, V , V Voltage .................... –0.3V to 2V
VLDO, VSTORE ............................................ –0.3V to 6V
VAUX......................................................15mA Into V
Operating Junction Temperature Range
(Note 2).................................................. –40°C to 125°C
Storage Temperature Range .................. –65°C to 125°C
INA INB
C1A, C1B Voltage ......................................... –0.3V to 6V
AUX
C2A, C2B Voltage (Note 6).............................. –8V to 8V
V
, V
.......................................... –0.3V to 6V
OUT2 OUT2_EN
VS1, VS2, V , PGOOD .............................. –0.3V to 6V
OUT
PIN CONFIGURATION
TOP VIEW
TOP VIEW
VS1
VS2
1
2
3
4
5
6
7
8
9
20
19
18
C1A
C2A
GND
20 19 18 17 16
VSTORE
VAUX
SWA
VSTORE
VAUX
1
2
3
4
5
15
14
13
12
11
V
17 SWA
INA
21
GND
V
V
V
OUT
16
15
14
13
12
11
V
V
INB
OUT
INA
INB
SWB
GND
V
OUT2
V
OUT2
V
OUT2_EN
V
SWB
GND
C2B
C1B
OUT2_EN
PGOOD
6
7
8
9 10
VLDO
GND 10
UF PACKAGE
20-LEAD (4mm s 4mm) PLASTIC QFN
GN PACKAGE
20-LEAD PLASTIC SSOP
T
= 125°C, θ = 37°C/W
JA
JMAX
T
= 125°C, θ = 90°C/W
JA
JMAX
EXPOSED PAD (PIN 21) IS GND (Note 5)
ORDER INFORMATION
LEꢃD FREE FIꢁISꢄ
LTC3109EUF#PBF
LTC3109IUF#PBF
LTC3109EGN#PBF
LTC3109IGN#PBF
TꢃPE ꢃꢁD REEL
PꢃRT MꢃRKIꢁG*
PꢃCKꢃGE DESCRIPTIOꢁ
TEMPERꢃTURE RꢃꢁGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
LTC3109EUF#TRPBF
LTC3109IUF#TRPBF
LTC3109EGN#TRPBF
LTC3109IGN#TRPBF
3109
20-Lead (4mm × 4mm) Plastic QFN
20-Lead (4mm × 4mm) Plastic QFN
20-Lead Plastic SSOP
3109
LTC3109GN
LTC3109GN
20-Lead Plastic SSOP
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/
3109fa
2
LTC3109
ELECTRICAL CHARACTERISTICS The l ꢂenotes the speAifiAations whiAh apply over the full operating
junAtion temperature range, otherwise speAifiAations are for Tꢃ = 251C (ꢁote 2). VꢃUX = 5V unless otherwise noteꢂ.
PꢃRꢃMETER
COꢁDITIOꢁS
MIꢁ
TYP
30
6
MꢃX
UꢁITS
mV
Minimum Start-Up Voltage
No-Load Input Current
Using 1:100 Transformer Turns Ratio, VAUX = 0V
50
Using 1:100 Transformer Turns Ratios,
mA
V
= 30mV, V
= 0V, All Outputs Charged
IN
OUT2_EN
and in Regulation
l
Input Voltage Range
Output Voltage
Using 1:100 Transformer Turns Ratios
V
500
mV
STARTUP
l
l
l
l
VS1 = VS2 = GND
2.30
3.234
4.018
4.875
2.350
3.300
4.100
5.000
2.40
3.366
4.182
5.10
V
V
V
V
VS1 = VAUX, VS2 = GND
VS1 = GND, VS2 = VAUX
VS1 = VS2 = VAUX
VAUX Quiescent Current
VAUX Clamp Voltage
No Load, All Outputs Charged
Current Into VAUX = 5mA
7
10
μA
V
l
l
5.0
6
5.25
0.2
5.55
V
OUT
V
OUT
Quiescent Current
Current Limit
V
OUT
V
OUT
= 3.3V, V
= 0V
OUT2_EN
μA
mA
Ω
= 0V
15
26
N-Channel MOSFET On-Resistance
C2B = C2A = 5V (Note 3) Measured from V or
0.35
INA
SWA, V or SWB to GND
INB
l
LDO Output Voltage
LDO Load Regulation
LDO Line Regulation
LDO Dropout Voltage
LDO Current Limit
0.5mA Load On V
2.134
2.2
0.5
0.05
100
12
2.30
1
V
%
LDO
For 0mA to 2mA Load
For V from 2.5V to 5V
0.2
200
%
AUX
l
l
I
= 2mA
= 0V
mV
mA
μA
mA
nA
V
LDO
V
5
6
LDO
VSTORE Leakage Current
VSTORE Current Limit
VSTORE = 5V
VSTORE = 0V
0.1
15
0.3
26
l
l
V
Leakage Current
V
OUT2
= 0V, V = 0V
OUT2_EN
50
OUT2
VS1, VS2 Threshold Voltage
VS1, VS2 Input Current
0.4
0.85
1
1.2
50
V
S1
= V = 5V
nA
%
S2
PGOOD Threshold (Rising)
PGOOD Threshold (Falling)
Measured Relative to the V
Measured Relative to the V
Sink Current = 100μA
Source Current = 0
Voltage
Voltage
–7.5
–9
OUT
%
OUT
PGOOD V
PGOOD V
0.12
2.2
1
0.3
2.3
V
OL
OH
2.1
0.4
V
PGOOD Pull-Up Resistance
MΩ
V
l
V
V
V
V
V
V
V
V
Threshold Voltage
V
Rising
1.0
100
5
1.3
OUT2_EN
OUT2_EN
OUT2_EN
OUT2_EN
Threshold Hysteresis
Pull-Down Resistance
mV
MΩ
μs
μs
A
Turn-On Time
0.5
0.15
0.3
350
1.0
OUT2
OUT2
OUT2
OUT2
OUT2
Turn-Off Time
(Note 3)
= 3.3V
l
Current Limit
V
OUT
0.2
0.5
Current Limit Response Time
P-Channel MOSFET On-Resistance
(Note 3)
= 5V (Note 3)
ns
Ω
V
OUT
ꢁote ꢀ: 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.
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
LTC3109I is guaranteed over the full –40°C to 125°C operating junction
temperature range. Note that the maximum ambient temperature
is determined by specific operating conditions in conjunction with
ꢁote 2: The LTC3109 is tested under pulsed load conditions such that
T ≈ T . The LTC3109E is guaranteed to meet specifications from
J
A
3109fa
3
LTC3109
ELECTRICAL CHARACTERISTICS
board layout, the rated thermal package thermal resistance and other
ꢁote 5: Failure to solder the exposed backside of the QFN package to the
PC board ground plane will result in a thermal resistance much higher
than 37°C/W.
environmental factors. The junction temperature (T ) is calculated from
J
the ambient temperature (T ) and power dissipation (P ) according to
A
D
the formula: T = T + (P • θ °C/W), where θ is the package thermal
impedance.
ꢁote ±: Specification is guaranteed by design and not 100% tested in
production.
J
A
D
JA
JA
ꢁote 6: The Absolute Maximum Rating is a DC rating. Under certain
conditions in the applications shown, the peak AC voltage on the C2A and
C2B pins may exceed 8V. This behavior is normal and acceptable because
the current into the pin is limited by the impedance of the coupling
capacitor.
ꢁote 4: Current measurements are made when the output is not switching.
TYPICAL PERFORMANCE CHARACTERISTICS Tꢃ = 251C, unless otherwise noteꢂ.
IIꢁ vs VIꢁ
IVOUT vs VIꢁ
PVOUT vs VIꢁ
10000
1000
100
100
10
1
1000
100
10
V
= 0V
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
1:50 RATIO
C1 = 4.7nF
OUT
V
= 3.3V
OUT
V
= 5V
OUT
NO LOAD ON VLDO
V
OUT
= 3.3V
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
10
0.1
1
10
100
(mV)
1000
10
100
V (mV)
IN
1000
10
100
(mV)
1000
V
V
IN
IN
3109 G02
3109 G18
3109 G01
Open-CirAuit Start-Up Voltage
vs SourAe ResistanAe
Input ResistanAe vs VIꢁ
EffiAienAy vs VIꢁ
50
45
40
35
30
25
20
15
10
5
90
80
70
60
50
40
30
20
10
0
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
V
= 0V
OUT
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
V
= 0V
OUT
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
0
10
100
(mV)
1000
10
100
1000
0
1
2
3
4
5
10
6
7
8
9
V
V
(mV)
SOURCE RESISTANCE (Ω)
IN
IN
3109 G04
3109 G03
3109 G05
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4
LTC3109
TYPICAL PERFORMANCE CHARACTERISTICS T = 251C, unless otherwise noteꢂ.
ꢃ
VꢃUX Clamp Voltage
vs Shunt Current
PVOUT vs ꢂT anꢂ TEG Size,
ꢀ:ꢀ33 Ratio, VOUT = 5V
VOUT anꢂ VLDO vs Temperature
5.5
5.4
5.3
5.2
5.1
5.0
1.00
3.0
2.5
0.75
0.50
FERROTEC 9500/127/100B
40mm
VLDO
2.0
1.5
0.25
0
V
OUT
–0.25
–0.50
–0.75
1.0
0.5
0
FERROTEC 9501/071/040B
22mm
–1.00
0
3
6
9
12
15
–25
0
50
75 100 125
0
1
2
3
4
5
6
7
8
9
10
–50
25
dT (°K)
VAUX SHUNT CURRENT (mA)
TEMPERATURE (°C)
3109 G07
3109 G06
3109 G08
Resonant SwitAhing Waveforms
LDO Loaꢂ Regulation
LDO Dropout Voltage
0.00
–0.25
–0.50
–0.75
–1.00
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
C1 A OR B
2V/DIV
C2 A OR B
2V/DIV
3109 G9
20μs/DIV
0
0.5
1.5
2
2.5
3
3.5
4
1
0
0.5
1.5
2
2.5
3
3.5
4
1
LDO LOAD (mA)
LDO LOAD (mA)
3109 G10
3109 G11
VOUT anꢂ PGOOD Response
During a Step Loaꢂ
Start-Up Voltage SequenAing
VOUT Ripple
V
= 50mV
50mA LOAD STEP
OUT
30μA LOAD
OUT
IN
1:100 RATIO TRANSFORMER
C
= 220μF
C
= 220μF
C
C
C
= 220μF
OUT
STORE
CH1
VSTORE
1V/DIV
= 470μF
= 2.2μF
LDO
CH2
OUT
1V/DIV
20mV/
DIV
V
CH2, V
OUT
1V/DIV
CH3, V
1V/DIV
CH1
PGD
1V/DIV
LDO
3109 G12
3109 G13
3109 G14
10SEC/DIV
5ms/DIV
100ms/DIV
3109fa
5
LTC3109
TYPICAL PERFORMANCE CHARACTERISTICS T = 251C, unless otherwise noteꢂ.
ꢃ
LDO Step Loaꢂ Response
Enable Input anꢂ VOUT2
Running on Storage CapaAitor
C
V
= 470μF
STORE
OUT
LOAD = 100μA
CH3
VSTORE
1V/DIV
V
LDO
CH2
OUT2
1V/DIV
20mV/DIV
V
CH2, V
OUT
1V/DIV
CH4, V
LDO
1V/DIV
I
CH1
OUT2_EN
1V/DIV
LDO
CH1, V
5mA/DIV
V
IN
50mV/DIV
3109 G16
3109 G17
3109 G15
200μs/DIV
1ms/DIV
5SEC/DIV
10mA LOAD ON V
OUT2
OUT
0mA TO 3mA LOAD STEP
LDO
C
= 220μF
C
= 2.2μF
PIN FUNCTIONS (QFꢁ/SSOP)
VSTORE(Pinꢀ/Pin±):OutputfortheStorageCapacitoror
Battery. A large storage capacitor may be connected from
this pin to GND for powering the system in the event the
input voltage is lost. It will be charged up to the maximum
VAUX clamp voltage. If not used, this pin should be left
open or tied to VAUX.
PGOOD (Pin 6/Pin 8): Power Good Output. When V
OUT
is within 7.5% of its programmed value, this pin will be
pulled up to the LDO voltage through a 1M resistor. If
V
drops 9% below its programmed value PGOOD will
OUT
go low. This pin can sink up to 100μA.
VLDO (Pin 7/Pin 9): Output of the 2.2V LDO. Connect a
2.2μF or larger ceramic capacitor from this pin to GND.
If not used, this pin should be tied to VAUX.
VꢃUX (Pin 2/Pin 4): Output of the Internal Rectifier Cir-
cuit and V for the IC. Bypass VAUX with at least 1μF of
CC
capacitance to ground. An active shunt regulator clamps
GꢁD (Pins 8, ꢀꢀ, ꢀ6, Exposeꢂ Paꢂ Pin 2ꢀ/Pins ꢀ3, ꢀ±,
ꢀ8):GroundPins.Connectthesepinsdirectlytotheground
plane.Theexposedpadservesasagroundconnectionand
as a means of conducting heat away from the die.
VAUX to 5.25V (typical).
V
(Pin ±/Pin 5): Main Output of the Converter. The
OUT
voltage at this pin is regulated to the voltage selected by
VS1 and VS2 (see Table 1). Connect this pin to a reservoir
capacitor or to a rechargeable battery. Any high current
pulse loads must be fed by the reservoir capacitor on
this pin.
VS2 (Pin 23/Pin 2): V
Select Pin 2. Connect this
OUT
pin to ground or VAUX to program the output voltage
(see Table 1).
VSꢀ (Pin ꢀ9/Pin ꢀ): V
Select Pin 1. Connect this
OUT
V
(Pin 4/ Pin 6): Switched Output of the Converter.
OUT2
pin to ground or VAUX to program the output voltage
Connect this pin to a switched load. This output is open
(see Table 1).
until V is driven high, then it is connected to V
OUT_EN
OUT
Table ꢀ. Regulateꢂ Output Voltage Using Pins VSꢀ anꢂ VS2
through a 1Ω PMOS switch. If not used, this pin should
VS2
GND
GND
VAUX
VAUX
VSꢀ
GND
VAUX
GND
VAUX
V
OUT
be left open or tied to V
.
OUT
2.35V
3.3V
4.1V
5.0V
V
(Pin 5/Pin 7): Enable Input for V
. V
OUT2 OUT2
OUT2_Eꢁ
will be enabled when this pin is driven high. There is an
internal 5M pull-down resistor on this pin. If not used,
this pin can be left open or grounded.
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6
LTC3109
PIN FUNCTIONS (DFꢁ/SSOP)
CꢀB(Pin9/Pinꢀꢀ):InputtotheChargePumpandRectifier
Circuit for Channel B. Connect a capacitor from this pin
to the secondary winding of the “B” step-up transformer.
SeetheApplicationsInformationsectionforrecommended
capacitor values.
SWꢃ (Pin ꢀ5/Pin ꢀ7): Connection to the Internal N-Chan-
nel Switch for Channel A. Connect this pin to the primary
winding of the “A” transformer.
SWB (Pin ꢀ2/Pin ꢀ4): Connection to the Internal N-Chan-
nel Switch for Channel B. Connect this pin to the primary
winding of the “B” transformer.
Cꢀꢃ (Pin ꢀ8/Pin 23): Input to the Charge Pump and Recti-
fierCircuitforChannelA. Connectacapacitorfromthispin
to the secondary winding of the “A” step-up transformer.
SeetheApplicationsInformationsectionforrecommended
capacitor values.
V
(Pinꢀ4/Pinꢀ6):ConnectiontotheInternalN-Channel
Iꢁꢃ
Switch for Channel A. Connect this pin to one side of the
input voltage source (see Typical Applications).
V
(Pinꢀ±/Pinꢀ5):ConnectiontotheInternalN-Channel
IꢁB
C2B (Pin ꢀ3/Pin ꢀ2): Input to the Gate Drive Circuit for
SWB. Connect a capacitor from this pin to the secondary
windingofthe“B”step-uptransformer.SeetheApplications
Information section for recommended capacitor values.
Switch for Channel B. Connect this pin to the other side of
the input voltage source (see Typical Applications).
C2ꢃ (Pin ꢀ7/Pin ꢀ9): Input to the Gate Drive Circuit for
SWA. Connect a capacitor from this pin to the secondary
windingofthe“A”step-uptransformer.SeetheApplications
Information section for recommended capacitor values.
3109fa
7
LTC3109
BLOCK DIAGRAM
SYNC
RECTIFY
C1B
V
REF
1.2V
REFERENCE
V
1Ω
OUT2
V
OUT2
SYNC
RECTIFY
V
OUT2_EN
V
C1A
OUT
V
OUT
•
•
+
5.25V
C
OUT
VS1
VS2
+
–
C2A
V
OUT
V
IN
PROGRAM
CHARGE
CONTROL
C2B
V
OUT
V
LDO
V
SWA
STORE
V
1M
INA
POWER
SWITCHES
V
+
–
REF
PG00D
•
•
SWB
PG00D
VSTORE
V
INB
+
V
OUT
C
STORE
LDO
V
REF
GND
VAUX
VLDO
2.2V
LDO
2.2μF
3109 BD
C
AUX
1μF
C
3109fa
8
LTC3109
OPERATION (Refer to the BloAk Diagram)
The LTC3109 is designed to use two small external
step-up transformers to create an ultralow input voltage
step-up DC/DC converter and power manager that can
operate from input voltages of either polarity. This unique
capability enables energy harvesting from thermoelectric
generators (TEGs) in applications where the temperature
differential across the TEG may be of either (or unknown)
polarity. It can also operate from low level AC sources. It
is ideally suited for low power wireless sensors and other
applications in which surplus energy harvesting is used to
generate system power because traditional battery power
is inconvenient or impractical.
Charge Pump anꢂ ReAtifier
The AC voltage produced on the secondary winding of
the transformer is boosted and rectified using an external
charge pump capacitor (from the secondary winding to
pin C1A or C1B) and the rectifiers internal to the LTC3109.
TherectifiercircuitfeedscurrentintotheV
ing charge to the external VAUX capacitor and the other
outputs.
pin, provid-
AUX
VꢃUX
The active circuits within the LTC3109 are powered from
VAUX, which should be bypassed with a 1μF minimum
capacitor. Once VAUX exceeds 2.5V, the main V
lowed to start charging.
The LTC3109 is designed to manage the charging and
regulation of multiple outputs in a system in which the
average power draw is very low, but where periodic pulses
of higher load current may be required. This is typical of
wireless sensor applications, where the quiescent power
drawisextremelylowmostofthetime,exceptfortransmit
pulses when circuitry is powered up to make measure-
ments and transmit data.
is al-
OUT
An internal shunt regulator limits the maximum voltage
on VAUX to 5.25V typical. It shunts to ground any excess
current into VAUX when there is no load on the converter
or the input source is generating more power than is
required by the load. This current should be limited to
15mA max.
The LTC3109 can also be used to trickle charge a standard
capacitor, super capacitor or rechargeable battery, using
energy harvested from a TEG or low level AC source.
Voltage ReferenAe
The LTC3109 includes a precision, micropower reference,
for accurate regulated output voltages. This reference
becomes active as soon as VAUX exceeds 2V.
Resonant OsAillator
The LTC3109 utilizes MOSFET switches to form a reso-
nant step-up oscillator that can operate from an input of
either polarity using external step-up transformers and
small coupling capacitors. This allows it to boost input
voltages as low as 30mV high enough to provide multiple
regulated output voltages for powering other circuits. The
frequency of oscillation is determined by the inductance
of the transformer secondary winding, and is typically
in the range of 10kHz to 100kHz. For input voltages as
low as 30mV, transformers with a turns ratio of about
1:100 is recommended. For operation from higher input
voltages, this ratio can be lower. See the Applications
Information section for more information on selecting
the transformers.
SynAhronous ReAtifiers
Once VAUX exceeds 2V, synchronous rectifiers in paral-
lel with each of the internal rectifier diodes take over the
job of rectifying the input voltage at pins C1A and C1B,
improving efficiency.
Low Dropout Linear Regulator (LDO)
The LTC3109 includes a low current LDO to provide a
regulated 2.2V output for powering low power proces-
sors or other low power ICs. The LDO is powered by
the higher of VAUX or V . This enables it to become
active as soon as VAUX has charged to 2.3V, while the
OUT
3109fa
9
LTC3109
OPERATION (Refer to the BloAk Diagram)
V
storage capacitor is still charging. In the event of a
PGOOD
OUT
step load on the LDO output, current can come from the
main V reservoir capacitor. The LDO requires a 2.2μF
ceramic capacitor for stability. Larger capacitor values
can be used without limitation, but will increase the time
it takes for all the outputs to charge up. The LDO output
is current limited to 5mA minimum.
A power good comparator monitors the V
voltage.
OUT
OUT
The PGOOD pin is an open-drain output with a weak pull-
up (1MΩ) to the LDO voltage. Once V
has charged
OUT
to within 7.5% of its programmed voltage, the PGOOD
output will go high. If V drops more than 9% from its
OUT
programmed voltage, PGOOD will go low. The PGOOD
output is designed to drive a microprocessor or other
chip I/O and is not intended to drive a higher current load
such as an LED. The PGOOD pin can also be pulled low in
a wire-OR configuration with other circuitry.
V
OUT
ThemainoutputvoltageonV ischargedfromtheVAUX
OUT
supply, and is user-programmed to one of four regulated
voltages using the voltage select pins VS1 and VS2, ac-
cording to Table 2. Although the logic-threshold voltage
for VS1 and VS2 is 0.85V typical, it is recommended that
they be tied to ground or VAUX.
V
OUT2
V
is an output that can be turned on and off by the
OUT2
host using the V
pin. When enabled, V
is con-
OUT2_EN
OUT2
nected to V
through a 1Ω P-channel MOSFET switch.
Table 2
OUT
This output, controlled by a host processor, can be used
to power external circuits such as sensors and amplifiers,
that don’t have a low power “sleep” or shutdown capabil-
OUT2
they are needed.
VS2
GND
GND
VAUX
VAUX
VSꢀ
GND
VAUX
GND
VAUX
V
OUT
2.35V
3.3V
4.1V
5V
ity. V
can be used to power these circuits only when
Minimizing the amount of decoupling capacitance on
OUT2
Whentheoutputvoltagedropsslightlybelowtheregulated
value,thechargingcurrentwillbeenabledaslongasVAUX
V
enables it to be switched on and off faster, allow-
ing shorter pulse times and therefore smaller duty cycles
is greater than 2.5V. Once V
has reached the proper
OUT
in applications such as a wireless sensor/transmitter. A
value, the charging current is turned off. The resulting
ripple on V is typically less than 20mV peak to peak.
small V
capacitor will also minimize the energy that
OUT2
OUT
will be wasted in charging the capacitor every time V
is enabled.
OUT2
The internal programmable resistor divider, controlled by
VS1 and VS2, sets V , eliminating the need for very
OUT
V
has a current limiting circuit that limits the peak
OUT2
high value external resistors that are susceptible to noise
current to 0.3A typical.
pickup and board leakages.
The V enable input has a typical threshold of 1V
OUT2
In a typical application, a reservoir capacitor (typically a
with 100mV of hysteresis, making it logic compatible. If
few hundred microfarads) is connected to V . As soon
OUT
V
(which has an internal 5M pull-down resistor)
OUT2_EN
is low, V
as VAUX exceeds 2.5V, the V
capacitor will begin to
OUT
will be off. Driving V
high will turn
OUT2_EN
OUT2
OUT2
charge up to its regulated voltage. The current available
to charge the capacitor will depend on the input voltage
and transformer turns ratio, but is limited to about 15mA
typical. Note that for very low input voltages, this current
may be in the range of 1μA to 1000μA.
on the V
output.
Note that while V
is high, the current limiting cir-
OUT2_EN
cuitry for V
draws an extra 8μA of quiescent current
OUT2
from V . This added current draw has a negligible effect
OUT
3109fa
10
LTC3109
OPERATION (Refer to the BloAk Diagram)
on the application and capacitor sizing, since the load on
Since the maximum charging current available at the
VSTORE output is limited to about 15mA, it can safely be
used to trickle charge NiCd or NiMH batteries for energy
storage when the input voltage is lost.
the V
output, when enabled, is likely to be orders of
OUT2
magnitude higher than 8μA.
VSTORE
Note that VSTORE is not intended to supply high pulse
The VSTORE output can be used to charge a large storage
load currents to V . Any pulse load on V
must be
OUT
OUT
capacitor or rechargeable battery. Once V
has reached
handled by the V
reservoir capacitor.
OUT
OUT
regulation, the VSTORE output will be allowed to charge
up to the clamped VAUX voltage (5.25V typical). The
storage element on VSTORE can then be used to power
the system in the event that the input source is lost, or
Short-CirAuit ProteAtion
All outputs of the LTC3109 are current limited to protect
against short circuits to ground.
is unable to provide the current demanded by the V
,
OUT
V
and LDO outputs.
OUT2
Output Voltage SequenAing
If VAUX drops below VSTORE, the LTC3109 will automati-
cally draw current from the storage element. Note that it
may take a long time to charge a large storage capacitor,
depending on the input energy available and the loading
Atimingdiagramshowingthetypicalchargingandvoltage
sequencing of the outputs is shown in Figure 1. Note that
the horizontal (time) axis is not to scale, and is used for
illustration purposes to show the relative order in which
the output voltages come up.
on V
and VLDO.
OUT
5.0
2.5
0
3.0
2.0
1.0
0
VSTORE
PGOOD
5.0
2.5
0
V
OUT
3.0
2.0
1.0
0
VLDO
VAUX
5.0
2.5
0
0
10
20
30
40
50
60
70
80
TIME (ms)
3109 F01
Figure ꢀ. Output Voltage SequenAing
(with VOUT Programmeꢂ for ±.±V). Time ꢁot to SAale
3109fa
11
LTC3109
APPLICATIONS INFORMATION
IꢁTRODUCTIOꢁ
ripple caused by the source’s ESR and the peak primary
switchingcurrent(whichcanreachhundredsofmilliamps).
Since the input voltage may be of either polarity, a ceramic
capacitor is recommended.
The LTC3109 is designed to gather energy from very low
input voltage sources and convert it to usable output
voltages to power microprocessors, wireless transmit-
ters and analog sensors. Its architecture is specifically
tailored to applications where the input voltage polarity is
unknown, or can change. This “auto-polarity” capability
makes it ideally suited to energy harvesting applications
using a TEG whose temperature differential may be of
either polarity.
PELTIER CELL (TꢄERMOELECTRIC GEꢁERꢃTOR)
A Peltier cell is made up of a large number of series-con-
nected P-N junctions, sandwiched between two parallel
ceramic plates. Although Peltier cells are often used as
coolers by applying a DC voltage to their inputs, they will
alsogenerateaDCoutputvoltage,usingtheSeebeckeffect,
when the two plates are at different temperatures.
Applications such as wireless sensors typically require
much more peak power, and at higher voltages, than
the input voltage source can produce. The LTC3109 is
designed to accumulate and manage energy over a long
period of time to enable short power pulses for acquiring
and transmitting data. The pulses must occur at a low
enough duty cycle that the total output energy during the
pulsedoesnotexceedtheaveragesourcepowerintegrated
over the accumulation time between pulses. For many
applications, this time between pulses could be seconds,
minutes or hours.
When used in this manner, they are referred to as thermo-
electricgenerators(TEGs).Thepolarityoftheoutputvoltage
will depend on the polarity of the temperature differential
between the TEG plates. The magnitude of the output volt-
age is proportional to the magnitude of the temperature
differential between the plates.
The low voltage capability of the LTC3109 design allows it
tooperatefromatypicalTEGwithtemperaturedifferentials
as low as 1°C of either polarity, making it ideal for harvest-
ing energy in applications where a temperature difference
exists between two surfaces or between a surface and
the ambient temperature. The internal resistance (ESR)
of most TEGs is in the range of 1Ω to 5Ω, allowing for
reasonablepowertransfer.ThecurvesinFigure2showthe
open-circuit output voltage and maximum power transfer
for a typical TEG with an ESR of 2Ω, over a 20°C range of
temperature differential (of either polarity).
The PGOOD signal can be used to enable a sleeping
microprocessor or other circuitry when V
reaches
OUT
regulation, indicating that enough energy is available for
a transmit pulse.
IꢁPUT VOLTꢃGE SOURCES
The LTC3109 can operate from a number of low input
voltage sources, such as Peltier cells (thermoelectric
generators), or low level AC sources. The minimum input
voltage required for a given application will depend on the
transformer turns ratios, the load power required, and the
internal DC resistance (ESR) of the voltage source. Lower
ESRsourceswillallowoperationfromlowerinputvoltages,
and provide higher output power capability.
1000
100
10
100
10
1
TEG: 30mm SQUARE
127 COUPLES
R = 2Ω
V
MAX P
OUT
(IDEAL)
OC
For a given transformer turns ratio, there is a maximum
recommended input voltage to avoid excessively high
secondary voltages and power dissipation in the shunt
regulator. It is recommended that the maximum input
voltage times the turns ratio be less than 50.
1
0.1
1
10
dT (°C)
100
3109 F02
Note that a low ESR decoupling capacitor may be required
acrossaDCinputsourcetopreventlargevoltagedroopand
Figure 2. TypiAal PerformanAe of a Peltier Cell
ꢃAting as a Power Generator (TEG)
3109fa
12
LTC3109
APPLICATIONS INFORMATION
TEG LOꢃD MꢃTCꢄIꢁG
UꢁIPOLꢃR ꢃPPLICꢃTIOꢁS
The LTC3109 was designed to present an input resistance
(load) in the range of 2Ω to 10Ω, depending on input volt-
age,transformerturnsratioandtheC1AandC2Acapacitor
values (as shown in the Typical Performance curves). For
a given turns ratio, as the input voltage drops, the input
resistance increases. This feature allows the LTC3109 to
optimize power transfer from sources with a few Ohms
of source resistance, such as a typical TEG. Note that a
lower source resistance will always provide more output
current capability by providing a higher input voltage
under load.
The LTC3109 can also be configured to operate from two
independent unipolar voltage sources, such as two TEGs
in different locations. In this configuration, energy can be
harvestedfromeitherorbothsourcessimultaneously.See
the Typical Applications for an example.
The LTC3109 can also be configured to operate from a
singleunipolarsource,usingasinglestep-uptransformer,
by ganging its V and SW pins together. In this manner,
IN
it can extract the most energy from very low resistance
sources. See Figure 3 for an example of this configuration,
along with the performance curves.
Table ±. Peltier Cell ManufaAturers
PELTIER CELL (TEG) SUPPLIERS
CUI Inc
www.cui.com
Peltiercellsareavailableinawiderangeofsizesandpower
capabilities, from less than 10mm square to over 50mm
square. They are typically 2mm to 5mm in height. A list
of some Peltier cell manufacturers is given in Table 3 and
some recommended part numbers in Table 4.
Ferrotec
www.ferrotec.com/products/thermal/modules/
Fujitaka
www.fujitaka.com/pub/peltier/english/thermoelectric_power.html
Hi-Z Technology
www.hi-z.com
Kryotherm
COMPOꢁEꢁT SELECTIOꢁ
Step-Up Transformer
www.kryotherm
Laird Technologies
www.lairdtech.com
Micropelt
www.micropelt.com
The turns ratio of the step-up transformers will determine
how low the input voltage can be for the converter to start.
Duetotheauto-polarityarchitecture,twoidenticalstep-up
transformersshouldbeused,unlessthetemperaturedrop
across the TEG is significantly different in one polarity, in
which case the ratios may be different.
Nextreme
www.nextreme.com
TE Technology
www.tetech.com/Peltier-Thermoelectric-Cooler-Modules.html
Tellurex
www.tellurex.com/
Table 4. ReAommenꢂeꢂ TEG Part ꢁumbers by Size
MꢃꢁUFꢃCTURER
CUI Inc. (Distributor)
Ferrotec
ꢀ5mm
23mm
±3mm
43mm
CP85438
CP60133
CP60233
CP60333
9501/031/030 B
FPH13106NC
9501/071/040 B
FPH17106NC
9500/097/090 B
FPH17108AC
TGM-127-1.0-0.8
PT6.7.F2.3030.W6
RC6-6-01
9500/127/100 B
FPH112708AC
LCB-127-1.4-1.15
PT8.12.F2.4040.TA.W6
RC12-8-01LS
Fujitaka
Kryotherm
Laird Technology
Marlow Industries
Tellurex
RC3-8-01
C2-20-0409
C2-15-0405
C2-30-1505
C2-40-1509
TE Technology
TE-31-1.0-1.3
TE-31-1.4-1.15
TE-71-1.4-1.15
TE-127-1.4-1.05
3109fa
13
LTC3109
APPLICATIONS INFORMATION
C1
T1
V
C1A
C2A
V
V
OUT2
IN
OUT2
•
•
+
1nF
LTC3109
V
C
IN
V
OUT
OUT
330k
+
C
OUT
SWA
VLDO
VLDO
2.2μF
V
INA
C1B
C2B
SWB
PG00D
PG00D
OUT2_EN
V
V
V
INB
OUT2_ENABLE
VS1
VS2
V
VSTORE
VAUX
OUT
SET
10μF
GND
NOTE: VALUES FOR C , T1, C1 AND C
3109 F03a
IN
OUT
ARE DETERMINED BY THE APPLICATION
Figure ±. Unipolar ꢃppliAation
TypiAal EffiAienAy vs VIꢁ for
Unipolar Configuration
TypiAal PVOUT vs ꢂT for Unipolar
Configuration
TypiAal IVOUT vs VIꢁ for Unipolar
Configuration
10000
1000
100
60
55
50
45
40
35
30
25
20
15
10
5
10
V
= 3.3V
FERROTEC 9500/127/100B, 40mm TEG
C1 = 33nF,
T1 = COILCRAFT LPR6235-123QML
1:50 RATIO
OUT
V
= 5V
OUT
V
= 3.3V
OUT
1
1:100, C1 = 6.8nF
1:50, C1 = 33nF
1:20, C1 = 68nF
1:100, C1 = 6.8nF
1:50, C1 = 33nF
1:20, C1 = 68nF
0
0.1
100
10
10
100
1000
10
10
100
V (mV)
IN
1000
dT (°K)
V
(mV)
IN
3109 F03f
3109 F03b
3109 F03c
TypiAal RIꢁ vs VIꢁ for Unipolar
Configuration
TypiAal Input Current vs VIꢁ for
Unipolar Configuration
600
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1:100, C1 = 6.8nF
1:50, C1 = 33nF
1:20, C1 = 68nF
550
500
450
400
350
300
250
200
150
100
50
1:100, C1 = 6.8nF
1:50, C1 = 33nF
1:20, C1 = 68nF
0
10
100
1000
10
100
(mV)
1000
V
(mV)
V
IN
IN
3109 F03d
3109 F03e
3109fa
14
LTC3109
APPLICATIONS INFORMATION
Using a 1:100 primary-secondary ratio yields start-up
voltages as low as 30mV. Other factors that affect per-
formance are the resistance of the transformer windings
and the inductance of the windings. Higher DC resistance
will result in lower efficiency and higher start-up volt-
ages. The secondary winding inductance will determine
the resonant frequency of the oscillator, according to the
formula below.
Cꢀ CꢃPꢃCITOR
The charge pump capacitor that is connected from each
transformer’s secondary winding to the corresponding
C1A and C1B pins has an effect on converter input resis-
tance and maximum output current capability. Generally
a minimum value of 1nF is recommended when operating
from very low input voltages using a transformer with
a ratio of 1:100. Capacitor values of 2.2nF to 10nF will
provide higher output current at higher input voltages,
however larger capacitor values can compromise perfor-
mance when operating at low input voltage or with high
resistance sources. For higher input voltages and lower
turns ratios, the value of the C1 capacitor can be increased
for higher output current capability. Refer to the Typical
Applications examples for the recommended value for a
given turns ratio.
1
Freq =
Hz
2 • π • LSEC •C
where L
is the inductance of one of the secondary
SEC
windings and C is the load capacitance on the second-
ary winding. This is comprised of the input capacitance
at pin C2A or C2B, typically 70pF each, in parallel with
the transformer secondary winding’s shunt capacitance.
The recommended resonant frequency is in the range of
10kHz to 100kHz. Note that loading will also affect the
resonant frequency. See Table 5 for some recommended
transformers.
C2 CꢃPꢃCITOR
The C2 capacitors connect pins C2A and C2B to their
respective transformer secondary windings. For most
applications a capacitor value of 470pF is recommended.
Smaller capacitor values tend to raise the minimum
start-up voltage, and larger capacitor values can lower
efficiency.
Table 5. ReAommenꢂeꢂ Transformers
TYPICꢃL STꢃRT-
VEꢁDOR
UP VOLTꢃGE
PꢃRT ꢁUMBER
Coilcraft
www.coilcraft.com
25mV
35mV
85mV
LPR6235-752SML (1:100 ratio)
LPR6235-123QML (1:50 ratio)
LPR6235-253PML (1:20 ratio)
Note that the C1 and C2 capacitors must have a voltage
rating greater than the maximum input voltage times the
transformer turns ratio.
Würth
www.we-online
25mV
35mV
85mV
S11100034 (1:100 Ratio)
S11100033 (1:50 Ratio)
S11100032 (1:20 Ratio)
USIꢁG EXTERꢁꢃL CꢄꢃRGE PUMP RECTIFIERS
ꢃꢁD VSTORE CꢃPꢃCITOR
V
OUT
The synchronous rectifiers in the LTC3109 have been
optimizedforlowfrequency,lowcurrentoperation,typical
of low input voltage applications. For applications where
the resonant oscillator frequency exceeds 100kHz, or a
transformer turns ratio of less than 1:20 is used, or the
C1A and C1B capacitor values are greater than 68nF, the
use of external charge pump rectifiers (1N4148 or 1N914
orequivalent)isrecommended.SeetheTypicalApplication
circuits for an example. Avoid the use of Schottky recti-
fiers, as their low forward voltage increases the minimum
start-up voltage.
For pulsed load applications, the V
be sized to provide the necessary current when the load
is pulsed on. The capacitor value required will be dictated
capacitor should
OUT
by the load current (I
PULSE
plication can tolerate (ΔV ). The capacitor must be
), the duration of the load pulse
LOAD
(t
), and the amount of V
voltage droop the ap-
OUT
OUT
rated for whatever voltage has been selected for V
VS1 and VS2:
by
OUT
I
LOAD(mA)• tPULSE(ms)
COUT(μF) ≥
ΔVOUT (V)
3109fa
15
LTC3109
APPLICATIONS INFORMATION
Note that there must be enough energy available from the
Note that storage capacitors requiring voltage balancing
resistors are not recommended due to the steady-state
current draw of the resistors.
input voltage source for V
to recharge the capacitor
OUT
during the interval between load pulses (as discussed in
Design Example 1). Reducing the duty cycle of the load
pulse will allow operation with less input energy.
PCB LꢃYOUT GUIDELIꢁES
The VSTORE capacitor may be of very large value (thou-
sands of microfarads or even Farads), to provide energy
storage at times when the input voltage is lost. Note that
this capacitor can charge all the way to the VAUX clamp
voltage of 5.25V typical (regardless of the settings for
Due to the rather low switching frequency of the resonant
converter and the low power levels involved, PCB layout
is not as critical as with many other DC/DC converters.
There are however, a number of things to consider.
Duetotheverylowinputvoltagesthecircuitoperatesfrom,
V
), so be sure that the holdup capacitor has a work-
OUT
the connections to V , the primary of the transformers
IN
ing voltage rating of at least 5.5V at the temperature that
it will be used.
and the SW, V and GND pins of the LTC3109 should be
IN
designed to minimize voltage drop from stray resistance,
and able to carry currents as high as 500mA. Any small
voltage drop in the primary winding conduction path will
lower efficiency and increase start-up voltage and capaci-
tor charge time.
The VSTORE input is not designed to provide high pulse
load currents to V . The current path from VSTORE to
OUT
V
is limited to about 26mA max.
OUT
The VSTORE capacitor can be sized using the following
formula:
Also, due to the low charge currents available at the out-
puts of the LTC3109, any sources of leakage current on
the output voltage pins must be minimized. An example
board layout is shown in Figure 4.
7μA +I +I + IPULSE • tPULSE • f • t
(
)
(
≥
)
Q
LDO
STORE
CSTORE
5.25 – VOUT
where 7μA is the quiescent current of the LTC3109, I is
Q
the load on V
in between pulses, I
is the load on
is the total load during the
OUT
LDO
the LDO between pulses, I
PULSE
pulse, t
is the duration of the pulse, f is the frequency
PULSE
of the pulses, t
is the total storage time required
STORE
and V
is the output voltage required. Note that for a
OUT
programmed output voltage of 5V, the VSTORE capacitor
cannot provide any beneficial storage time to V
.
OUT
To minimize losses and capacitor charge time, all capaci-
tors used for V
and VSTORE should be low leakage.
OUT
See Table 6 for recommended storage capacitors.
Table 6. ReAommenꢂeꢂ Storage CapaAitors
VEꢁDOR
PꢃRT ꢁUMBER/SERIES
AVX
BestCap Series
Figure 4. Example Component PlaAement for 2-Layer PC Boarꢂ
(QFꢁ PaAkage). ꢁote That VSTORE anꢂ VOUT CapaAitor Sizes
are ꢃppliAation Depenꢂent
www.avx.com
TAJ and TPS Series Tantalum
Cap-XX
www.cap-xx.com
GZ Series
KR Series
Cooper/Bussman
www.bussmann.com/3/PowerStor.html P Series
Vishay/Sprague
www.vishay.com/capacitors
Tantamount 592D
595D Tantalum
3109fa
16
LTC3109
APPLICATIONS INFORMATION
DESIGꢁ EXꢃMPLE ꢀ
To calculate the maximum rate at which load pulses can
occur, you must know how much charge current is avail-
This design example will explain how to calculate the
able from the LTC3109 V
pin given the input voltage
OUT
necessary reservoir capacitor value for V
in pulsed-
OUT
source being used. This number is best found empirically,
since there are many factors affecting the efficiency of the
converter. You must also know what the total load cur-
load applications, such as a wireless sensor/transmitter.
In these types of applications, the load is very small for a
majority of the time (while the circuitry is in a low power
sleep state), with pulses of load current occurring periodi-
cally during a transmit burst.
rent is on V
during the sleep state (between pulses).
OUT
Note that this must include any losses, such as storage
capacitor leakage.
The reservoir capacitor on V
supports the load during
OUT
Let’s assume that the charge current available from the
the transmit pulse; the long sleep time between pulses
allows the LTC3109 to accumulate energy and recharge
the capacitor (either from the input voltage source or the
storagecapacitor).Amethodforcalculatingthemaximum
rate at which the load pulses can occur for a given output
current from the LTC3109 will also be shown.
LTC3109 is 150μA and the total current draw on V
and
OUT
VLDOinthesleepstateis17μA,includingcapacitorleakage.
We’ll also use the value of 330μF for the V capacitor.
OUT
The maximum transmit rate (neglecting the duration of
the transmit pulse, which is very short compared to the
period) is then given by:
In this example, V
is set to 3.3V, and the maximum
OUT
330μF • 0.33V
150μA – 17μA
allowed voltage droop during a transmit pulse is 10%, or
0.33V. The duration of a transmit pulse is 5ms, with a total
average current requirement of 20mA during the pulse.
Given these factors, the minimum required capacitance
T =
= 0.82sec or fMAX = 1.2Hz
Therefore, in this application example, the circuit can sup-
port a 5ms transmit pulse of 20mA every 0.82 seconds.
on V
is:
OUT
It can be seen that for systems that only need to transmit
every few seconds (or minutes or hours), the average
charge current required is extremely small, as long as
the sleep or standby current is low. Even if the available
charge current in the example above was only 21μA, if the
sleep current was only 5μA, it could still transmit a pulse
every seven seconds.
20mA • 5ms
0.33V
COUT μF ≥
( )
= 303μF
NotethatthisequationneglectstheeffectofcapacitorESR
on output voltage droop. For ceramic capacitors and low
ESR tantalum capacitors, the ESR will have a negligible
effectattheseloadcurrents.However,bewareofthevoltage
coefficientofceramiccapacitors, especiallythoseinsmall
case sizes. This greatly reduces the effective capacitance
when a DC bias is applied.
The following formula will allow you to calculate the time
it will take to charge the LDO output capacitor and the
V
OUT
capacitor the first time, from zero volts. Here again,
the charge current available from the LTC3109 must be
known. For this calculation, it is assumed that the LDO
output capacitor is 2.2μF:
A standard value of 330μF could be used for C
in
OUT
this case. Note that the load current is the total current
draw on V , V and VLDO, since the current for all
OUT OUT2
of these outputs must come from V
during a pulse.
2.2V • 2.2μF
ICHG – ILDO
OUT
tLDO
=
Current contribution from the capacitor on VSTORE is not
considered, since it may not be able to recharge between
pulses. Also, it is assumed that the harvested charge
current from the LTC3109 is negligible compared to the
magnitude of the load current during the pulse.
If there was 150μA of charge current available and a 5μA
loadontheLDO(whentheprocessorissleeping), thetime
for the LDO to reach regulation would be only 33ms.
3109fa
17
LTC3109
APPLICATIONS INFORMATION
The time for V
to charge and reach regulation can be
In this example, I is 5μA, I
and T is one hour. The average charge current required
from the LTC3109 would be:
is 100mA, t
is 5ms
OUT
Q
PULSE
PULSE
calculated by the formula below, which assumes V
is
OUT
programmed to 3.3V and C
is 330μF:
OUT
3.3V • 330μF
ICHG –IVOUT –ILDO
100mA • 0.005sec
tVOUT
=
+ tLDO
ICHG ≥ 5μA +
= 5.14μA
3600sec
Therefore, if the LTC3109 has an input voltage that allows
it to supply a charge current greater than just 5.14μA, the
application can support 100mA pulses lasting 5ms every
hour. It can be seen that the sleep current of 5μA is the
dominant factor in this example, because the transmit
With 150μA of charge current available and 5μA of load on
both V and VLDO, the time for V to reach regula-
OUT
OUT
tion after the initial application of power would be 7.81
seconds.
duty cycle is so small (0.00014%). Note that for a V
OUT
DESIGꢁ EXꢃMPLE 2
of 3.3V, the average power required by this application is
only 17μW (not including converter losses).
Inmostpulsed-loadapplications, theduration, magnitude
and frequency of the load current pulses are known and
fixed. In these cases, the average charge current required
from the LTC3109 to support the average load must be
calculated, which can be easily done by the following:
Keep in mind that the charge current available from the
LTC3109 has no effect on the sizing of the V
capacitor,
OUT
and the V
capacitor has no effect on the maximum
OUT
allowed pulse rate.
IPULSE • tPULSE
ICHG ≥IQ +
T
where I is the sleep current supplied by V
and V
LDO
Q
OUT
to the external circuitry in-between load pulses, including
output capacitor leakage, I is the total load current
PULSE
during the pulse, t
is the duration of the load pulse
PULSE
and T is the pulse period (essentially the time between
load pulses).
3109fa
18
LTC3109
TYPICAL APPLICATIONS
Energy ꢄarvester Operates from Small Temperature Differentials of Either Polarity
TEG
(THERMOELECTRIC GENERATOR)
30mV TO 500mV
T1
1:100
1nF
C1A
V
OPTIONAL SWITCHED OUTPUT FOR SENSORS
3.3V
OUT2
•
•
•
•
470pF
C2A
V
OUT
+
2.2V
470μF
SWA
VLDO
2.2μF
V
LOW POWER
RADIO
INA
T2
1:100
1nF
LTC3109
C1B
SENSOR(S)
μP
470pF
C2B
PG00D
SWB
INB
V
OUT2_EN
V
5.25V
VS1
VS2
VSTORE
VAUX
+
1μF
C
STORE
GND
3109 TA02
T1, T2: COILCRAFT LPR6235-752SML
Li-Ion Battery Charger anꢂ LDO Operates from a Low Level ꢃC Input
50mV TO
300mV RMS
T1
1:100
1nF
C1A
V
OUT2
•
•
•
•
470pF
60Hz
AC
C2A
V
TO LOAD
OUT
2.2V
SWA
VLDO
VLDO
2.2μF
LTC4070*
FAIRCHILD
FDG328P
V
INA
LBO
HBO
NC
NC
NC
T2
1:100
1nF
LTC3109
NTC
DRV
4.1V
C1B
V
NTCBIAS
CC
470pF
+
NC
ADJ
Li-Ion
BATTERY
GND
C2B
PG00D
SWB
INB
VS1
VS2
V
OUT2_EN
V
*THE LTC4070 IS A PRECISION BATTERY
CHARGER OFFERING UNDERVOLTAGE
PROTECTION, WITH A TYPICAL SUPPLY
CURRENT OF ONLY 0.45μA
T1, T2: COILCRAFT
LPR6235-752SML
VSTORE
VAUX
1μF
GND
3109 TA03
3109fa
19
LTC3109
TYPICAL APPLICATIONS
Unipolar Energy ꢄarvester Charges Battery BaAkup
THERMOELECTIC
GENERATOR
T1
1:50
33nF
FERROTEC 9500/127/100B
+
C1A
C2A
V
OUT2
•
•
47μF
–
1nF
V
OUT
V
OUT
3.3V
+
330μF
4V
330k
LTC3109
2.2V
SWA
VLDO
VLDO
V
INA
2.2μF
T1: COILCRAFT
LPR6235-123QML
C1B
C2B
SWB
INB
VS1
VS2
PGOOD
PG00D
V
OUT2_EN
TypiAal PVOUT vs ꢂT for Unipolar
Configuration
V
VSTORE
VAUX
FAIRCHILD
FDG328P
LTC4070
LBO HBO
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
NC
NC
NC
1μF
FERROTEC 9500/127/100B
C1 = 33nF
GND
NTC
DRV
4.1V
T1 = COILCRAFT LPR6235-123QML
1:50 RATIO
OUT
V
NTCBIAS
CC
+
NC
ADJ
V
= 3.3V
Li-Ion
BATTERY
GND
3109 TA06a
0
1
2
3
4
5
6
7
8
9
10
dT (°K)
3109 TA06b
Dual-Input Energy ꢄarvester Generates 5V anꢂ 2.2V from Either or Both TEGs,
Operating at Different Temperatures of Fixeꢂ Polarity
COILCRAFT
LPR6235-752SML
1:100
1nF
C1A
C2A
V
OUT2
+
–
•
•
THERMOELECTRIC
GENERATOR
25mV TO 500mV
470pF
LTC3109
V
5V
V
OUT
OUT
+
SWA
C
*
OUT
V
INA
COILCRAFT
LPR6235-123QML
1:50
2.2V
4.7nF
VLDO
VLDO
2.2μF
C1B
+
–
•
•
THERMOELECTRIC
GENERATOR OR
THERMOPILE
470pF
C2B
SWB
PG00D
OUT2_EN
PG00D
1μF
35mV TO 1000mV
V
V
INB
VS1
VS2
VSTORE
VAUX
GND
3109 TA04
*THE VALUE OF THE C
CAPACITOR IS
OUT
DETEMINED BY THE LOAD CHARACTERISTICS
3109fa
20
LTC3109
PACKAGE DESCRIPTION
Please refer to http://www.linear.Aom/ꢂesigntools/paAkaging/ for the most reAent paAkage ꢂrawings.
UF PaAkage
23-Leaꢂ PlastiA QFꢁ (4mm w 4mm)
(Reference LTC DWG # 05-08-1710 Rev A)
0.70 0.05
4.50 0.05
3.10 0.05
2.45 0.05
2.00 REF
2.45 0.05
PACKAGE OUTLINE
0.25 0.05
0.50 BSC
PIN 1 NOTCH
R = 0.20 TYP
OR 0.35 w 45°
CHAMFER
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
BOTTOM VIEW—EXPOSED PAD
R = 0.05
TYP
R = 0.115
0.75 0.05
TYP
4.00 0.10
19 20
0.40 0.10
PIN 1
TOP MARK
(NOTE 6)
1
2
2.45 0.10
2.00 REF
4.00 0.10
2.45 0.10
(UF20) QFN 01-07 REV A
0.200 REF
0.25 0.05
0.50 BSC
0.00 – 0.05
NOTE:
1. DRAWING IS PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220
VARIATION (WGGD-1)—TO BE APPROVED
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
3109fa
21
LTC3109
PACKAGE DESCRIPTION
Please refer to http://www.linear.Aom/ꢂesigntools/paAkaging/ for the most reAent paAkage ꢂrawings.
Gꢁ PaAkage
23-Leaꢂ PlastiA SSOP (ꢁarrow .ꢀ53 InAh)
(Reference LTC DWG # 05-08-1641 Rev B)
.337 – .344*
(8.560 – 8.738)
.058
(1.473)
REF
.045 .005
20 19 18 17 16 15 14 13 12 11
.254 MIN
.150 – .165
.229 – .244
.150 – .157**
(5.817 – 6.198)
(3.810 – 3.988)
.0165 .0015
.0250 BSC
1
2
3
4
5
6
7
8
9 10
RECOMMENDED SOLDER PAD LAYOUT
.015 .004
(0.38 0.10)
.0532 – .0688
(1.35 – 1.75)
.004 – .0098
(0.102 – 0.249)
w 45s
.0075 – .0098
(0.19 – 0.25)
0° – 8° TYP
.016 – .050
(0.406 – 1.270)
.008 – .012
.0250
(0.635)
BSC
(0.203 – 0.305)
GN20 REV B 0212
TYP
NOTE:
1. CONTROLLING DIMENSION: INCHES
INCHES
(MILLIMETERS)
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
3109fa
22
LTC3109
REVISION HISTORY
REV
DꢃTE
DESCRIPTIOꢁ
PꢃGE ꢁUMBER
A
06/12 Added vendor Information to Table 5
15
3109fa
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.
23
LTC3109
TYPICAL APPLICATION
IVOUT vs VIꢁ
16
14
12
10
8
1:20 RATIO
C1 = 1μF
TYPICAL
EXTERNAL DIODES
Unipolar TEG Energy ꢄarvester for Low ResistanAe/ꢄigh Current Inputs,
Using External Charge Pump ReAtifiers
VAUX
COILCRAFT
LPR6235-253PML
1:20
1.0μF
6
BAS31
SWITCHED V
GOES HIGH
OUT
+
4
WHEN PGOOD IS HIGH
C1A
C2A
V
V
OUT2
OUT2
2
•
•
0.1μF
1nF
LTC3109
V
70mV TO 1V
0
3.3V
2.2V
V
0
100
400 500
200 300
600 700
800
OUT
OUT
+
SWA
V
(mV)
IN
C
OUT
V
INA
3109 TA05b
VLDO
VLDO
C1B
EffiAienAy vs VIꢁ
2.2μF
50
45
40
35
30
25
20
15
10
5
C2B
PG00D
PG00D
SWB
V
OUT2_EN
V
INB
VS1
VS2
VAUX
VSTORE
VAUX
+
10μF
C
STORE
GND
3109 TA05
0
10
100
1000
V
(mV)
IN
3109 TA05c
RELATED PARTS
PꢃRT ꢁUMBER
DESCRIPTIOꢁ
COMMEꢁTS
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,
OUT Q
IN
4mm × 3mm DFN-12, SSOP-16; LTC3108-1 V
= 2.2V, 2.5V, 3V, 3.7V, 4.5V
OUT
LTC4070
Micropower Shunt Battery Charger
1% Float Voltage Accuracy, 50mA Max Shunt Current, V
Q
= 4.0V, 4.1V, 4.2V,
OUT
I = 450nA, 2mm × 3mm DFN-8, MSOP-8
LTC1041
LTC1389
Bang-Bang Controller
V : 2.8V to 16V; V
= Adj; I = 1.2mA; I < 1μA; SO-8 Package
IN
OUT(MIN) Q SD
Nanopower Precision Shunt Voltage Reference
V = 1.25V; I = 0.8μA; SO-8 Package
OUT(MIN) Q
LT1672/LT1673/
LT1674
Single-/Dual-/Quad-Precision 2μA Rail-to-Rail
Op Amps
SO-8, SO-14 and MSOP-8 Packages
LT3009
3μA I , 20mA Linear Regulator
V : 1.6V to 20V; V : 0.6V to Adj, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V,
Q
IN
OUT(MIN)
5V to Fixed; I = 3μA; I < 1μA; 2mm × 2mm DFN-8 and SC70 Packages
Q
SD
LTC3588-1
LT8410/LT8410-1
Piezoelectric Energy Generator with Integrated
High Efficiency Buck Converter
V : 2.7V to 20V; V
: Fixed to 1.8V, 2.5V, 3.3V, 3.6V; I = 0.95μA;
IN
OUT(MIN) Q
3mm × 3mm DFN-10 and MSOP-10E Packages
Micropower 25mA/8mA Low Noise Boost Converter V : 2.6V to 16V; V
with Integrated Schottky Diode and Output
Disconnect
= 40V
; I = 8.5μA; I < 1μA;
MAX Q SD
IN
OUT(MIN)
2mm × 2mm DFN-8 Package
3109fa
LT 0612 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
24
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© LINEAR TECHNOLOGY CORPORATION 2010
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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