1. Energy Harvesting Multi-source Demoboard with Transducers (DC2080A) Brian Shaffer Applications Manager Boston Design Center Linear Technology Corporation Phone:
Hi… Thank you for participating in this Webinar today… My name is Brian Shaffer… I am the Applications Manager at Linear Technology’s Boston Design Center. The following will be a discussion about the Energy Harvesting Multi-Source Demoboard with Transducers… inside the Energy Harvesting “TO GO” Design Kit, which was developed by Linear Technology, Wurth Electronik and Energy Micro.

2. Outline
What is the DC2080A,
Energy Harvesting (EH) Multi-Source Demoboard
Available Power from Typical Energy Harvesting Sources
Energy Harvesting Power Management Circuits
LTC3588-1: Piezoelectric Energy Harvesting Power Supply.
LTC3108: Ultralow Voltage Step-Up Converter and Power Manager.
LTC3105: Step-Up DC/DC Converter with Power Point Control and LDO Regulator.
LTC3459: 10V Micropower Synchronous Boost Converter with Input Voltage Regulation.
LTC2935-2,-4: Ultralow Power Supervisor with Power-Fail Output Selectable Thresholds.
Schematic and BOM for Reference
Conclusion
I will describe the overall function of the Multi-source demoboard… talk about the Energy Harvesting sources the demoboard can accommodate and finish off with a review of the power management circuits and their key performance features.

3. Power Management Board
What is the DC2080A
Power Management Board
for the
Energy Harvesting
“TO GO”
DESIGN KIT
Demo Circuit 2080 is the power management demoboard that will ship with the Energy Harvesting Design Kit, orderable directly from Wurth Electronik. Current versions of the kit are available with the BCB190-2, which is substantially similar to the 2080A. The fabrication documents and Demo Manual for demo circuit 2080 will be available for download within 4 weeks of this presentation. Please look for them on Linear Technology's demoboard web page and on the Wurth landing page for the Energy Harvesting “TO GO” Design Kit.

4. What is the DC2080A
Energy Harvesting Multi-Source Demoboard with Transducers
Allowable Sources
PIEZOELECTRIC TRANSDUCER
ELECTROMECHANICAL TRANSDUCER
THERMAL ELECTRIC GENERATOR
4-20mA LOOP
PHOTOVOLTAIC CELLS
VIN Range
3.5 Ohms - 40K Ohms
VOUT Average
<50mA, Typically 20uA to 1mA
Demo Circuit 2080A Multi-Source Demoboard contains all the power management circuits and support circuitry needed to condition Piezoelectric transducers, Electromechanical transducers, High impedance AC mains, Thermal Electric Generators, 4-20mA loop power, or Photovoltaic cells into usable energy. In addition it contains two integrated transducers, a CUI Incorporated TEG and a Panasonic AM5412 solar panel. Either of which can be used for immediate demonstration results.
By selecting the correct inputs, the board accommodates input sources as low as 20mV with a source impedance of 4 Ohms… to ones that generate 200 Volts with a source impedance of 40 thousand Ohms or greater. All the power management circuits are configured to regulate at 3.3 Volts. Some of the outputs can deliver up to 50mA, but the typical average operating condition for wireless sensor nodes is 20uA to 1mA.
The picture on the right hand side shows the top of the assembled board.
If the integrated transducers are not needed, demo circuit 2042A, available from Linear Technology’s Web Site, is the equivalent of the bottom half. The Demo Manual and Fabrication documents are available on Linear Technology’s Demoboard web page.
Top Assembly

5. What is the DC2080A
Energy Harvesting Multi-Source Demoboard with Transducers
Allowable Sources
PIEZOELECTRIC TRANSDUCER
ELECTROMECHANICAL TRANSDUCER
THERMAL ELECTRIC GENERATOR
4-20mA LOOP
PHOTOVOLTAIC CELLS
VIN Range
3.5 Ohms - 40K Ohms
VOUT Average
<50mA, Typically 20uA to 1mA
The bottom side of the board contains some helpful optional components. There is a large capacitor bank available to use for energy storage… or to accommodate peak current requirements during high power events such as transmitter send and receive intervals, sensor measurements or one time network joining requirements. In addition, there are unpopulated Or-ing diodes that would allow more than one Energy Harvesting source to be connected at the same time. The most powerful source or the one with the highest output voltage setting would supply the load energy.
Bottom Assembly

6. Available Sources How Much Power is Available?
The power density of Energy Harvesting Sources limit the available power they can deliver. Typical Energy Harvesting transducers for Wireless Sensor Nodes are designed to deliver an average current between 10uA and 1mA. In other applications, the transducers may be designed to deliver currents well beyond that range. From this graph, ranking the sources from most powerful to least we get:
1) Outside Sun
2) Thermal gradients
3) Inside Sun
4) Stress or Strains
5) Vibrations
6) Thermal Variations
7) Infrared
8) Biochemistry
and finally
9) RF
High impedance line supplies could be placed anywhere into this list, depending on the series resistance used.

7. LTC3588-1: Piezoelectric Energy Harvesting Power Supply (VIBRATION or High-impedance AC-sources)
Key Features:
Integrated rectifier converts piezo AC output to DC ( extremely low leakage )
500nA UVLO circuit allows input cap to be charged up before DC/DC enabled – ensures reliable startup
Synchronous step-down DC/DC operates over wide VIN and load current with high efficiency
Overvoltage shunt protects input – dumps excess energy to GND at VIN > 20V
1uA (typ) no load ICC minimizes wasted energy at low vibration levels
High impedance AC sources are conditioned by the LTC It has an extremely low quiescent current, 950nA when regulating Vout at no load. Its DC/DC converter input voltage range is from 2.7 Volts to 18 Volts and contains an internal bridge rectifier that can handle 50mA of average current. The internal 20 Volt shunt protects the device from high impedance sources with open circuit voltages greater than its ABS Max rating. The output voltage is selectable between 1.8, 2.5, 3.3 or 3.6 Volts by changing two digital inputs.

8. LTC3108: TEG powered Energy Harvester
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
Unipolar TEG sources are conditioned by the LTC The LTC3108 operates from as low as 20mV. In order to have good power transfer, the TEG must have a source impedance of less than 10 Ohms so that it is closely matched to the input impedance of the resonant circuit made up of T1,C8, C11,R13 and the SW pin, which is approximately 3.5 Ohms. The IC contains a power path controller that manages the Energy storage between LDO, VOUT and VSTORE. Demo circuit 2080 has the option of connecting the large capacitor bank on the bottom to either VOUT or STORE. The output voltage is selectable between 2.35, 3.3, 4.1 or 5.0 Volts by changing two digital inputs.
If bipolar operation is required, where the polarity of the thermal gradient changes with time, then the LTC3109 can be used.

9. LTC3108 Voltage Sequencing (Measurements)
Power Up Power Down
VIN
VLDO: 2.2V fixed
VOUT: 2.35V, 3.3V, 4.1V or 5V
(LTC3108 & LTC3109)
VOUT: 2.5V, 3.0V, 3.7V, 4.5V
(LTC3108-1)
VSTORE charges up to 5.25V
VSTORE
VOUT
VLDO
This scope shot shows the power path circuirty at work, prioritizing the location of where the input energy is first stored. The priority is set as LDO then VOUT and finally VSTORE.
© 2011, Linear Technology Corporation

10. LTC3105: supplied by diode voltage drop in 4-20mA loop
Synchronous Boost Converter + LDO starts up at 250mV
Includes Maximum Power Point Control (MPPC), which adjusts
the peak inductor current to maintain Vin at a programmed voltage
Operates from higher resistance sources than traditional boosts
Uses burst-mode architecture with variable Ipk and Ivalley
The LTC3105 is a Synchronous Boost Converter plus LDO that starts up with only 250mV on its input. The Maximum Power Point Control function regulates the input voltage to a set value established by the selection of the resistor on its MPPC pin. A fixed current of 10uA is sourced into this resistor and establishes the input voltage regulation point. Because of this input voltage regulation loop, the part is able to accommodate higher impedance sources than say the LTC3108 or LTC It can be used for high impedance TEGs, Solar Panels or a Low voltage source, as demonstrated here with a diode drop in a 4-20mA loop.

11. LTC3459 supplied by solar cell
>85% Efficiency over Wide Load Range
Internal Synchronous Rectifier
VIN Range: 1.72V to 3.3V
Burst Mode Operation
Inrush Current Limiting
Output Disconnect in Shutdown
Ultralow Quiescent (10μA) and Shutdown (<1μA) Current
The LTC3459 is a 10uA Synchronous Boost Converter. The added LTC2935-4, ultra-low power supervisor with selectable thresholds, implements the MPPC function, which was built into the It can also be used for high impedance TEGs and Solar Panels from 1.72 Volts to 3.3 Volts. The inrush current limiting makes it well suited for low power sources. The output disconnect in shutdown ensures that the output capacitor will not be discharged back to the input when the source is not generating energy.

12. Detailed Schematic of PGOOD_LTC3459 Circuit using LTC2935-2
In addition to having the option of routing the PGOOD signal from each of the power management circuits to the header, the demo circuit provides an independent PGOOD signal and VOUT disconnect function. The RST output from the LTC provides the independent PGOOD signal and the VOUT disconnect function via Q3. This signal is also the PGOOD signal for the LTC3459 circuit. The VOUT disconnect function is active at all times. This function is very important for many low power processors as they do not like to see slowly rising voltages below 1.5 Volts. The LTC circuit connects VOUT to the load, when VOUT reaches 3.15 Volts and disconnects VOUT when VOUT reaches 2.25 Volts. The wide hysteresis window is generated by connecting the S2 input to the RST bar output via R35.
500nA Quiescent Current
±1.5% (Max) Accuracy over Temperature
Integrated Precision Attenuators
Eight Pin-Selectable Reset Thresholds
Eight Pin-Selectable Power-Fail Thresholds

13. DC2080A Schematic Vibration or High-Impedance AC Thermal Electric
Energy Storage
Optional:
Optional:
PGOOD
Pulse Circuit
Thermal
Electric
Generator
(Rs=3.5Ohms)
4-20mA Loop
(Lower-Voltage
Solar)
This is the complete schematic of the Energy Harvester multi-Source Demoboard. The Demo manual and fabrication drawings will be available from both the Linear Technology and Wurth Electronik web sites.
Optional:
PGOOD
Pulse Circuit
3.15Volts
VSUPPLY
Volts
Lower-Voltage
Solar

14. Linear Technology Energy Harvesting Products – Power Capability
Maximum Output Power*
VIN Range
LTC3588-1
Iq = 950nA
LTC3588-2
Iq = 1.5uA
LTC3108
Iq=6uA
LTC3109
Iq = 6uA
LTC3105
Iq =24uA
LTC3388-X
Iq = 720nA
LTC4071
Iq = 550nA
UVLO_Rising<VIN<=18V
0.36W (3.6V*100mA)
0.5W (5.0V*100mA)
Vin>18V
90mW (18V*5mA)
2.7V<VIN<=20V
0.25W
VIN=0.6V
10mW (2.8mA*3.3V)
15mW
Vcc<=Vshunt
Vin=3V
500mW
(Vout=5V)
Vin=1V
290mW
This slide contains the power capabilities of additional components to consider when doing ultra-low power designs. The LTC3388 is a 20 Volt, 720nA Synchronous Buck converter.
The LTC4071 is a 50mA shunt Li-Ion battery charger with low battery disconnect. The quiescent current of the LTC4071 is 500nA while operational and draws only pico-amps from the battery when the battery hits its low battery disconnect threshold.
*Provided the source is capable of delivering the required power to overcome the inefficiency of the power converter

15. LTC Energy Harvesting Solutions
Energy source
Transducers
LTC Power
Management ICs
Typical POUT
@ VOUT = 3.3V
Maximum POUT
Indoor Solar
(200lux – 1000lux)
Photovoltaic Cells (100cm2)
LTC3105
LTC4071
LTC3129
LTC3459
100uW – 1mW
>100mW
Outdoor Solar
(1000lux – 50000lux)
LTC3588
1mW – 100mW
Thermal
(10oC – 30oC dT)
TEGs (100cm3)
LTC3108
LTC3109
200uW – 1.4mW
>10mW
Vibration
(Piezo: 0.1g – 1g)
(EM: 0.025g – 0.5g)
Piezoelectric (30cm2)
Electromechanical (200cm3)
50uW – 500uW
500uW – 10mW
This slide contains similar information but with the part numbers organized by Energy Harvester Source.

16. Conclusion
The DC2080A Multi-Source Demoboard contains power management circuits and support circuitry to condition:
Piezoelectric
Electromechanical
High impedance AC mains
Thermal Electric Generators
4-20mA loop power
Photovoltaic cells
If the Integrated Transducers are not needed consider the DC2042A
The Multi-Source Demoboard contains power management circuits and support circuitry to condition:
Piezoelectric transducers
Electromechanical transducers
High impedance AC mains
Thermal Electric Generators
4-20mA loop power and
Photovoltaic cells
If the Integrated Transducers are not needed consider the DC2042A…
Thank you for attending this webinar today.
Thank You