02 Energy-Harvesting - Jedes System Erfordert Ein Individuell Optimiertes Konzept

Energy Harvesting Jedes System erfordert ein individuell

optimiertes Konzept

Linear Technology

Bostjan Bitenc, Field Application Engineer

© 2011, Linear Technology Corporation

Ludwigsburg, 6. Juli 2011

Agenda

2 © 2011, Linear Technology Corporation

Energy Harvesting Basics

• General • Thermal • Vibration • Solar

Energy Harvester Products and Solutions

• Thermal • Vibration • Solar • Other Limited Sources

Summary

Practical Demonstrations

Energy Harvesting – what is it?


Free Energy….

But The Laws of Physics Still Apply !

Energy Harvesting Goals


Charge, supplement or replace batteries in systems where battery use is inconvenient, impractical, expensive or dangerous

Eliminate the need for wires to carry power or to transmit data

Smart wireless sensor networks to monitor and optimize complex industrial processes, remote field and building installations ( e.g. HVAC, light switches )

Various consumer electronic accessory chargers

Harvesting otherwise wasted heat from industrial processes, solar panels, internal combustion engines, etc.

Energy Harvesting Sources


Thermo-Electric Generator or Thermopile (Heat)

Piezoelectric (Motion / Vibration creates strain)

Photovoltaic (Light)

Galvanic (Moisture)

Coil/Magnet (Motion / Vibration / Induction)

Courtesy of TOKO Inc.


Outdoor

Indoor

Piezoelectric

Electrostatic

Magnetic

Man

Machine

GSM

WiFi

Harvested

Power

Potential Up to

0.1 uW/cm2

Up to

10,000 uW/cm2

(10 mW/cm2)

Up to

100,000 uW/cm2

(100 mW/cm2)

Up to

1,000 uW/cm2

(1 mW/cm2)



RF Vibration Thermal Photovoltaic

Where an Energy Harvester Fits in


Remote industrial sensor networks

HVAC monitoring and control

Building automation

Predictive maintenance

Avionics

Automatic/remote metering

Military, Aerospace, Commercial, Medical sensors

“Free” Energy

Source /

Transducer

Power

Conversion /

Energy

Management

Sensors,

A/D,

controller

Wireless

transmitter /

receiver

THE MISSING LINK

First Think About Your Needs

Source /

Transducer

Power

Conversion

Sensor

Controller

Wireless

XCVR

Sensor Node Power Requirements:

• Supply Voltage: Vs

• Continuous Current: Ic

• Additional Pulsed Current: Ip

• Pulse Duration: tp

• System On Time: ton

• Number of Sequences: N

• Sequence Duty Cycle: DC

Total Energy Bill:

AVGtotalAVG

i

pipioncStotal

total

DCEt

EP

tItIVE

dtIVE

*

)**(*

**

,,

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100 120 140 160

P[uW]


Then Think About Your Capabilities

Source /

Transducer

Power

Conversion

Sensor

Controller

Wireless

XCVR

Source Characteristics:

• What is the main energy source parameter for the transducer (ΔT, Flux, Strain, ...)?

• How stable is the energy source over time?

• How does the transducer matches the energy source itself (e.g. TEG size vs. ΔT)?

• How much energy can you derive with the parameters given above?

• What kind of system parameters have influence on the transducer efficiency (e.g. heat vs. efficiency for solar cells)?

• What is the transducer output impedance resp. output voltage and waveform?

Light Flux

10

100

1.000

10.000

0 5 10 15 20 25 30

Voc

(mV)

dT (Deg C)

TEG Open Circuit Voltage vs dT

2" TEG

1.5" TEG

0.625" TEG


And Then Try to Match Both

Source /

Transducer

Power

Conversion

Sensor

Controller

Wireless

XCVR

Input Power

Output Power

Conversion and Leakage Losses

Voltage Conversion DC or AC

to DC

e.g.

50mV 3.3V

Buffering Source & Load Profile Averaging

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100 120 140 160

P[uW]

0

200

400

600

800

1000

1200

1400

1600

1800

0 20 40 60 80 100 120 140 160

PIN[uW]


Load Matching Basics


Pout vs Load Resistance

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6 7 8 9 10

Load Resistance (Ohms)

Po

ut

(mW

)

Rsource = 3 Ohms

Rsource = 1 Ohm

Where is the sweet spot for maximum power transfer between Source and Load?

sourceload RR

Back to School Basics:

What is the transferred power at that point?

load

loadsource

INOUT R

RR

VP *

2

loadR

sourceR

Matching Example: TEG


Effect of Rsource on Vin & Pout, for Voc=100mV & Rin=3 Ohms

0.1

1

10

100

1000

10000

1 10 100 1,000

Rsource (Ohms)

Vin

(m

V)

or

Po

ut

(uW

)Pout (uW)

Vin (mV)

RIN : input impedance of the DCDC

Load Matching by decoupling the output load from the source with the harvester

What if the Impedances doesn‘t match?


Over time decouple output and input:

e.g. Caps/battery to buffer energy

Over source parameter control harvester input power: e.g. Maximum power point control

Storage Cap collects charge during Sensor Idle State.

Acts as low impedance source when Power is needed.

Adjust current to keep the input at the desired voltage.

Effectively raises the input resistance of the Harvester when the load is overdriving the source.

Known as MPPC for Solar Cells.

Aux Cap collects charge before enabling VOUT control

Agenda






Summary


Cooling With Peltier Elements


• Peltier elements have for a long time been used for

active cooling

• A temperature difference is created by applying a voltage

Known applications :

• Hotel refrigerators

• Electronics heat sinks

• Cooling of laser diodes

• …

Thermal Harvesting With Peltier Elements


• Doing the opposite, generating a voltage from a

temperature difference is called the Seebeck effect

• Thermo electric generator [ TEG ]


• Voltage is proportional to temperature difference

• The length and area of each elements sets its basic

properties as thermal and electrical resistance

• The P-N elements are connected in series in a module

• Series connection gives higher voltage (and resistance)

• From thermal point of view, they are connected in

parallel

Thermal Harvesting Using Seebeck Effect


Thermal Model of a System

Thermo-Electric Model of a System


ΔT=(Thot-Tcold)xRteg/(Rsource+Rteg+Rsink)


TEG Datasheet Example


TEG Datasheet Example


Thermoelectric coolers

• Many parameters needed for optimization not given

• Seebeck voltage not given (Voc as function of temperature)

• Thermal resistance not given

They do however work as TEGs

• Seebeck voltage easily measured

• Thermal resistance can be estimated or measured, even

though more difficult, or simply oversize the heatsink to

make the TEGs thermal resistance neglectable

• Oversizing the TEG gives unpredictable and often poor

results

TEC vs. TEG Datasheets

Manufacturer 15 x 15 mm 20 x 20 mm 30 x 30 mm 40 x 40 mm

CUI Inc (Distributor) CP60133 CP60233 CP60333 CP85438

Ferrotec 9501/031/030 B 9501/071/040 B 9500/097/090 B 9500/127/100 B

Fujitaka FPH13106NC FPH17106NC FPH17108AC FPH112708AC

Kryotherm TGM-127-1.0-0.8 LCB-127-1.4-1.15

Laird Technology PT6.7.F2.3030.W6 PT8.12.F2.4040.TA.W6

Marlow Industries RC3-8-01 RC6-6-01 RC12-8-01LS

Tellurex C2-15-0405 C2-20-0409 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

Recommended TEG Part Numbers by Size

TEC ≡ TEG

an N-P pair is called a “couple”

Typical Thermoelectric Cooler (TEC) Module Sizes


Agenda






Summary


What is Piezoelectricity?


Applying mechanical strain to certain solid materials results in energy generation.


Piezoelectric Energy Harvesting

Piezoelectric materials convert strain (deflection, displacement vibration) into electrical energy

Piezoelectric generators – What’s available?


Piezoelectric generators – What you need to know


• Vibrating generators produce an A/C output voltage.

• Electrical output depends on frequency and acceleration.

• Open circuit voltages may be quite high at high g-levels.

• Output impedances can also be high.

• Physical size of the generator dictates energy produced

and optimum frequency of oscillation.


Source: Adaptive Energy Corporation

Source: Advanced Cerametrics Corporation

Frequency response must match or power falls off quickly

Piezo generators are easily tuned for 10 - 300Hz resonance and provide µW’s to mW’s of power at 0.1g to 2g acceleration levels

The Importance of Resonance (Natural Frequency)

Vibration Sources


Vibration Source

Acceleration

[m/s^2] g-Level

Frequency

[Hz]

Car engine compartment 12 1.22 200

Car Instrument Panel 3 0.31 13

Base of 3-Axis machine tool 10 1.02 70

Kitchen Blender 6.4 0.65 121

Clothes Dryer 3.5 0.36 121

Door Frame just as door closes 3 0.31 125

Small microwave oven 2.25 0.23 121

HVAC vents in office building 0.2-1.5 0.02 - 0.15 60

Wooden deck with foot traffic 1.3 0.13 385

Bread maker 1.03 0.11 121

External windows (size 2' x 3')

next to busy street 0.7 0.07 100

Notebook computer while CD is

being read 0.6 0.06 75

Washing Machine 0.5 0.05 109

Second story floor of a wood

frame office building 0.2 0.02 100Refrigerator 0.1 0.01 240

Reference: Seminario “RFId: sensors e energy harvesting” – LIUC

Universita Carlo Cattaneo – 5 giugno 2009

Design Example: Vibration Powered Wireless Sensor Node


How can I replace this…

…with this?

Motivation: reduce high maintenance costs

Good News: Application energy/power requirements are low


Typical Application: 3 sensor wireless monitor

Energy requirements: 482uJ total

Transmitting every 10 seconds requires 48.2uW (482uJ / 10s)

Source: Microstrain Corporation

Improving technology → lower power

How much power can piezo transducers generate ?


Characterization of Available Vibration Energy

35 © 2011, Linear Technology Corporation Source: Mide Corporation

Agenda






Summary


Solar Cells – Different Types


Solar Cell – How It Works


Solar cells are basically PN junctions (diodes). Their typical IV curve exhibits fairly constant current dependent on illumination levels

(Do-It-Yourself Method)

Load

Solar Cell Maximum Power Point


In an open circuit (no load current), power is 0.

In a short circuit (no load voltage), power is 0.

In between these extremes there is a “sweet spot” where maximum power is extracted

from the cell.

How do we keep the solar cell in the maximum power

point?

Solar Cells Maximum Power Point And Illumination Intensity


o Light levels can vary by over three orders of magnitude

o Maximum Power Point (MPP) voltage varies vs. illumination intensitiy …

o Maximum Power Point Tracking (MPPT) useful to maximize cell output

o DC/DC converter input current regulation to achieve MPP voltage o … and varies much more

vs. cell temperature

Light Levels vs Time & Place

10 100 1,000 10,000 100,000 1,000,000

Cloudy day in unlit room

Lab bench

Cloudy day in cube

Lab bench top shelf

Sunny day in cube near windows

Cloudy day outside at 5PM

Cloudy day outside at 1PM

Sunny day inside next to window 2PM

Sunny day outside aimed straight up at 10AM

Sunny day outside aimed straight up at 2PM

Sunny day outside aimed at the sun 10AM

Illuminance (Lux)

MPPC implementation in a power converter


• MPP is the Photovoltaic (PV) cell equivalent of load matching

• For most PV cells, the MPP voltage is ~70 to 80% of the open circuit voltage (Voc)

• Load matching is achieved by regulating the INPUT voltage of the power converter

(output of PV cell) equal to the Maximum Power Point (MPP) voltage of the PV cell.

VMPP

Agenda






Summary


Thermal Energy Harvesting Products


LTC3108/-1: Ultra-Low Voltage (20mV) Step-Up converter and Power Manager

• Operates from inputs as low as 20mV

• Alternate Fixed Output Voltages

• Unique Resonant Power converter / Energy Harvester

• Auxiliary LDO

• Manages Energy storage between Reservoir and Main Cout or Batt

• Compact Step-up Transformer

• 3x4mm DFN or GN16 packages

LTC3108 - 20mV Resonant Boost Topology


• 20mV Operation or ~1deg dT if powered from a Peltier Effect Thermal Electric Generator (TEG or TEC)

• LTC proprietary MOSFET makes extreme low voltage possible

• Input-Circuit self-oscillates, resonant step-up circuit

• Built-in Synchronous rectification improves Energy harvesting “yield”

• 1:100 transformer is standard part ( Wuerth, Coilcraft, Cooper Bussmann )

Typical Resonant Waveforms ( Measurements )


VSW 50mV/div (Vin=50mV)

ISW 20mA/div

VSEC 2V/div

VC1 2V/div

Note: “soft-switching”

Choose transformer ratio based on Vin

-min Vin < 50mV, use 1:100 ratio

- min Vin > 50mV, use 1:50 ratio

- min Vin > 200mV, use 1:20 ratio

Typical Resonant Waveforms ( Simulation )


LTspice schematic : Typical simulation result :

Output-Voltage Sequencing ( VAUX & VLDO )


• VAUX powers active circuits within

LTC3108 ( e.g. VAUX >2V activates the

synchronous rectifier to improve

efficiency of power conversion ).

after VAUX reaches 2V3

• VLDO fixed 2V2 for low-power µC or

other low power ICs (ILDO ~ 3mA)

ramp up

Output-Voltage Sequencing ( VOUT & CSTORE )


3. COUT is charged up to the programmed

output-voltage; a PGOOD-Signal

indicates when VOUT is within 7.5%

of this voltage.

after VOUT has reached regulation

after VLDO reaches 2V2

4. A capacitor or rechargeable battery

connected to VSTORE stores the

remaining energy. Storage element can

be used to power system in the event

that the input source is lost.

LTC3108 Feature: Harvested Energy Management


• VOUT2 is a switched ON-OFF version of VOUT for sensors that don’t have a SD input

• Harvested energy is preferentially sent to VOUT

• Excess harvested energy is sent to VSTORE

• VSTORE will backfeed VOUT in the event of a power outage

• Charge control block provides all of the intelligence to ensure seamless operation

LTC3108 Voltage Sequencing (Simulation)


Datasheet LTC3108 ( page 11 ) : Simulation result :

LTC3108 Voltage Sequencing (Measurements)


VLDO

VOUT

VSTORE

VIN

Power Up Power Down

o VLDO: 2.2V fixed

o VOUT: 2.35V, 3.3V, 4.1V or 5V

(LTC3108 & LTC3109)

o VOUT: 2.5V, 3.0V, 3.7V, 4.5V

(LTC3108-1)

o VSTORE charges up to 5.25V

LTC3108 Feature: Digital Selection of VOUT


• Eliminates multi-M resistors from the PCB

• Easier manufacturability

• Predictable and stable VOUT

• Other combinations possible with option mask (contact the factory)

Block Diagram of LTC3108


VOUT: Main Output

Charge Control and Prioritizer

VSTORE: Energy Reservoir

VOUT2: Switched VOUT

Digital Vout Select

3mA LDO:

uController power

Rectifier

Compact Step-Up transformer

20mV Vin Source

VAUX: Intermediate Charge storage and IC bias supply

Depletion mode MOSFET

Dave Salerno Artikel

+ LINK


http://cds.linear.com/docs/LT%20Journal/LTJournal_V20N3_Oct10.pdf

http://cds.linear.com/docs/LT Journal/LTJournal_V20N1_Apr10.pdf


Typical Setup for LTC3108/-1


Uni-polar: Vin > 20mV

TEG

Sensors, µC, RF Link

TEG Reference Data

56

Remember: Bigger TEG doesn’t always mean more available power!

16 x16 mm

40 x 40 mm

54 x 54 mm

Input Resistance LTC3108


• Rin of the LTC3108 converters is in

the range of 2.5 – 5Ω, it varies with

Vin & transformer ratio

• Traditional TEGs, with a resistance

of 0.5 – 3Ω, provide a good match

to the converter

Sources with much higher source-resistance will provide only very little

power because of source-load-mismatch.

TEG Thermal Resistance


Thermal connections are important

make sure that

RTEG >> RHS + RS

to get the maximum temperature-

difference at the TEG-Element

LTC3109: Auto Polarity Ultra-Low Voltage Step-Up converter and Power Manager

• Operates from inputs as low as +/- 30mV

• Proprietary Auto-Polarity Architecture

• Unique Resonant Power converter / Energy Harvester

• Auxiliary LDO

• Manages Energy storage between Reservoir and Main Cout or Batt

• Compact Step-up X-former

• 4x4mm QFN or GN20 packages

LTC3109 = LTC3108 with 2 resonant input stages


Block Diagram of LTC3109


Proprietary Ultra-low

voltage AutoPolarity

Architecture

(Patent Pending)

VOUT and Digital

select

Power GOOD

VSTORE: Charge

Storage Reservoir

Switched VOUT

2.2V Ultra-Low Iq LDO

Harvested Energy Manager

Two depletion mode mosfets

Typical LTC3109 Auto-Polarity Application


o Typical startup voltage of ±30mV

o Operates equally well from either polarity

o Can operate from a low frequency AC input

o Uses two identical transformers

o Same basic control architecture as the LTC3108

Typical LTC3109 Uni-Polar App


LTC3109 in Uni-Polar Configuration Iout vs Vin

10

100

1,000

10,000

10 100 1,000

Vin (mV)

Iou

t (u

A)

1:100, C1=6.8nF

1:50, C1=33nF

1:20, C1=68nF

Ivout vs Vin Comparison of LTC3108 & LTC3109 (1:100)

0

500

1000

1500

2000

2500

3000

0 50 100 150 200 250 300

Vin (mV)

Ivo

ut

(uA

)

LTC3109, uni-polar config

LTC3108

o Can be configured for uni-polar operation

o Typical startup voltage of just 15mV !

o Uses a single transformer

o Generates ~3x the current of the LTC3108 for the same Vin ( by paralleling MOSFETs)

Typical Setup for LTC3109


Autopolarity: Vin > ±30mV

(or Uni-polar: Vin>15mV)

o Basically 2 x LT3108 in one package

o Uses two resonant step-up cores to process positive and negative voltages

o Second resonant core can be configured for positive input voltage ( 2 x output power + lower Vin startup )

o Designed for low resistance sources (< 5Ω)

LTC3108 & LTC3109 Step-Up Transformers From Coilcraft


Agenda






Summary


Specifying a Piezo for a Wireless Sensor Node (WSN)


Answers to the above questions will enable piezo suppliers to provide or design the proper transducer

- Vibration Source Characteristics What is the source vibration frequency ?

What is the min, typ and max acceleration that the WSN must operate under ?

- Application Electrical Characteristics How much energy does the WSN require ?

initial network configuration

steady state sensor measurement and transmission power

How frequently does the WSN transmit ?

sets average operating power

What is the turn-on threshold for the power management device ?

sets the minimum VOC of the piezo at the source frequency and minimum acceleration

- Application Physical Constraints How much area can be dedicated to mounting the piezo element ?

How much height will be allocated for the piezo and its enclosure ?

What type of mounting does the application require ?

What are the environmental conditions (moisture, temperature,…) ?

Converting Harvested Energy into a Regulated Output


Rectification Options:

– Full-bridge

• Piezo current conducts on both phases

• Best for high open circuit voltage conditions

– “Doubler”

• Piezo current conducts on positive phase only

• Best for low open circuit voltages

Step 1: Convert piezo AC output to an unregulated DC (VRECT) supply

DC/DC Tradeoffs

Conversion Efficiency vs. Quiescent Current


DC/DC Goals:

– Maximize VRECT to VOUT conversion efficiency over input voltage and VOUT load

conditions (Switching Converter)

– Minimize quiescent current (LDO, e.g. LT6656 )

– Key Consideration: Keep the application (VOUT) powered at minimum vibration

levels!

VRECT varies widely with

vibration and load

Applications typically

need a regulated supply

Use or store as much harvested energy as possible Minimize all sources of non-load power consumption

Charge Storage Considerations (1)


Energy Stored at DC/DC input

- PROs

• Can utilize high voltage energy storage (E = ½ *C *V2)

• High voltage ceramic capacitors (low leakage)

• Combine with SuperCaps on the output for extended run times

- CONs

• Higher vibration requirement to achieve high input voltage

• Power from source not optimized by adjusting charge current

3588-1 turns on

too early, -2 solves

this issue by having

A higher ULVO threshold

Charge Storage Considerations (2)


Energy Stored at DC/DC Output

- PROs

• SuperCaps or batteries can be used at low voltages

• Low vibration requirement due to low operating voltage

• Modify charge current to optimize power output from source (MPPT…)

- CONs

• Low voltage energy storage requires larger capacitance

• Long charge times

Start-Up Concerns


Piezo RS is typically

HIGH (10kOhm – 100kOhm+)

DC/DC operating current

is highest at startup

Net Result:

VRECT and VOUT

both stuck LOW!

One More Problem: Overvoltage


DC/DC’s have

max VIN specs

VOC and VRECT climb at high

vibration levels and low

DC/DC load current

Integrated Solution

LTC3588 Piezoelectric Energy Harvester


Key Features: o Integrated rectifier converts piezo AC output to

DC ( extremely low leakage )

o 500nA UVLO circuit allows input cap to be charged up before DC/DC enabled – ensures reliable startup

o Synchronous step-down DC/DC operates over wide VIN and load current with high efficiency

o Overvoltage shunt protects input – dumps excess energy to GND at VIN > 20V

o 1uA (typ) no load ICC minimizes wasted energy at low vibration levels

Can be RF coupled

Extremely low leakage rectifier

( not possible with discrete

components )

Performance Advantages of Integrated Solution


…this is very hard to do with discrete components !

Typical Startup and Recharge Waveforms

75

Measurement :

3.3V regulator start-up profile

Simulation ( time adjusted ) :

Startup and recharge after load step

Dave Salerno Artikel

+ LINK


http://cds.linear.com/docs/LT%20Journal/LTJournal_V20N1_Apr10.pdf




Agenda






Summary


High Efficiency Solar Energy Harvester


o Synchronous Boost Converter + LDO starts up at 250mV

o Includes Maximum Power Point Control (MPPC), which adjusts

the peak inductor current to maintain Vin at a programmed voltage

o Operates from higher resistance sources than traditional boosts

o Uses burst-mode architecture with variable Ipk and Ivalley

LTC3105: Block Diagram Review



http://cds.linear.com/docs/LT%20Journal/LTJournal-V21N1-2011-04.pdf









LTC3105 : Maximum Power Point Control Simplified


simple single resistor programming

diode provides easy temperature compensation

thermally coupled to solar cells,1 diode / solar cell

o Maximum Power Point Control circuit servo’s Vin to equal V(MPPC)

o V(MPPC) = 10uA x R(MPPC)

o Set V(MPPC) = ~ 75% of Voc

Boost Converter without MPPC – Startup Example


Solar Cell is Overloaded and circuit will not start

LTC3105 MPP Control Startup Example


Solar Cell is regulated to Max Power Point

½ the peak of the previous example.

Good to add a cap to buffer initial peak. MPPC loop regulates down input current

Vin does not come close to UVLO threshold

LTC3105 Typical Wireless Sensor Node Application


SHDN used to stop the LTC3105 switching for a short period of time in order to measure or transmit data.

LTC3105 Output Power at Indoor Light Levels


10

100

1000

10000

0 100 200 300 400 500 600 700 800 900 1000

Ou

tpu

t P

ow

er

(uW

)

Lux

161uW

Only ~200 Lux required to meet example application limits with some cells

100 cm²

50 cm²

25 cm²

LTC3105 Max Output Power vs Lux with various Thin Film solar cells

Vout=3.3V, 4 cell in series, approx 25/50/100 cm²

o LTC3105 boosts the low solar panel output voltage to a higher voltage to allow charging

o LTC4070 shunt battery charger limits the maximum battery voltage to 4.2V

o NTC thermistor reduces the battery float voltage in 100mV steps at high temperatures

o P-FET disconnects the load to prevent damaging the battery from over discharge

Complete Low Power Solar Li-Ion Battery Charger


%

LTC3105 Charge Current For Varying Sunlight

Without MPPC


These curves show the results of a reduction in sunlight on the solar panel output

voltage & the LTC3105 charge current. For a 15% drop in sunlight intensity, the

charge current dropped to 0mA. Without maximum power point control, the

LTC3105 boost converter pulled the solar panel voltage very low resulting in zero

output power.

.

Relative Sunlight Intensity

Solar Panel

Output Current

Solar

Panel

Output

Voltage

LTC3105

Charge

Current

600mA

400mA

200mA

0

60mA

40mA

20mA

0

1V

0.8V

0.6V

0.4V

0.2V

0

100%

Changing Sunlight Intensity Effects on Charge Current

(With Maximum Power Point Control)

Battery Voltage = 3.6V

10 seconds

Ch

arg

e C

urr

en

t (m

A)

So

lar P

an

el O

utp

ut (V

)

100%

Pa

nel

Ou

tpu

t (m

A)

LTC3105 Charge Current For Varying Sunlight

With MPPC


These curves show the results of a reduction in sunlight on the solar panel output

voltage & the LTC3105 charge current. For a 15% drop in sunlight intensity, the

charge current dropped to approximately 50mA. The maximum power point control

prevents the solar panel voltage from dropping below 750mV.

LTC3105 Energy Harvester


Power

Source

IN

Main

VOUT Auxiliary LDO VOUT

Main

VOUT

GOOD

Flag

Advantages of

Integrated Power Management Solutions


…this is very hard to do with discrete components!

Single IC replaces up 35 discrete components, multiple functions

Predictable and reliable operation in harsh Industrial environments

Integrated MOSFETs optimized for speed and ultra-low Iq

Multi-MΩ Resistors integrated, no manufacturability concerns

Off the shelf Integrated Solutions for all types of practical transducers

Compatible with all types of storage elements

Agenda






Summary



LTC3105: Non-PhotoVoltaic Application Circuit

Power from diode drop voltage


LTC3108: Non-Thermal Application Circuit

Power from small voltage drop

e.g. interconnection resistance

current

Vdro

p


LTC3109: Non-Thermal Application Circuit

Power from small AC voltage !

e.g. output of Rogowski coil

• Photo diode sourced by light fiber ( 3105 )

• Using primary cell to death ( 3105 )

• Charge with galvanic elements ( 3105, 3108 )

e.g. from lemon ( see youtube videos )

• Magnetic field harvesting ( 3588 )

e.g. stray field of transformers

• …


Many More Application Circuits …

It is up to you to find more application areas !

Agenda






Summary


Summary

What Linear Technology Can Do for You


o Different sources with varying impedances need especially adopted IC‘s

o Each IC is optimized for special sources regarding Conversion Topology

and Input Impedance

o IC‘s are maximized for conversion efficiency to give you the most output

power available from the source !

Documents

02 Energy-Harvesting - Jedes System Erfordert Ein Individuell Optimiertes Konzept