1. Day 5: Energy Applications - Energy Conversion and Management Silicon
Energy Harvesting
Day 5: Energy Applications - Energy Conversion and Management Silicon
April 19, 2013 Paul Nickelsberg Orchid Technologies Engineering and Consulting, Inc.

2. Energy Harvesting Review
Energy harvesting is the process of capturing trace amounts of naturally occurring energy from various sources.
Accumulating the Energy
Storing the Energy
Applying the Energy for Useful Purpose

3. Energy Applications Energy Source Energy Management Energy Application3

4. Energy Applications 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:
Courtesy Linear Technologies Corporation 4

5. Energy Applications
Where is the sweet spot for maximum power transfer between Source and Load?
What is the transferred power at that point?
Courtesy Linear Technologies Corporation 5

6. Energy Applications
Over time  decouple output and input: e.g. Caps/battery to buffer energy
Storage Cap collects charge during Sensor Idle State.
Acts as low impedance source when Power is needed. 1 2
Aux Cap collects charge before enabling VOUT control
Over source parameter  control harvester input power e.g. Maximum power point control
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. 3
Courtesy Linear Technologies Corporation 6

7. Energy Applications Circuit Collections
Rechargeable Lithium
Thin Film Battery
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application.
Source: Cymbet 7

8. Energy Applications Circuit Collections
Advanced Linear Devices ALD110902
Source: Advanced Linear Devices
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 8

9. Energy Applications Circuit Collections
Seiko S-882Z
Source: Seiko
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 9

10. Energy Applications Circuit Collections
Seiko S-882Z
Source: Seiko
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 10

11. Energy Applications Circuit Collections
Source: Mide
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 11

12. Energy Applications Circuit Collections
Solar Cell
or TEG
Source: Texas Instruments
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 12

13. Energy Applications Circuit Collections
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
Courtesy Linear Technologies Corporation
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 13

14. Energy Applications Circuit Collections
VOUT2: Switched VOUT
Rectifier
20mV Vin Source
VOUT: Main Output
Digital Vout Select
Compact Step-Up transformer
Depletion mode MOSFET
VSTORE: Energy Reservoir
3mA LDO:
uController power
Courtesy Linear Technologies Corporation
VAUX: Intermediate Charge storage and IC bias supply
Charge Control and Prioritizer
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 14

15. Energy Applications Circuit Collections
LTC3588 Piezoelectric Energy Harvester
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
Courtesy Linear Technologies Corporation
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 15

16. Energy Applications Circuit Collections
High Efficiency Solar Energy Harvester
Synchronous Boost Converter + LDO starts up at mV
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
Courtesy Linear Technologies Corporation
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 16

17. Energy Applications Circuit Collections
LTC3105: Block Diagram
Courtesy Linear Technologies Corporation
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 17

18. Energy Applications Circuit Collections
LTC3105 boosts the low solar panel output voltage to a higher voltage to allow charging
LTC4070 shunt battery charger limits the maximum battery voltage to 4.2V
NTC thermistor reduces the battery float voltage in 100mV steps at high temperatures
P-FET disconnects the load to prevent damaging the battery from over discharge
Courtesy Linear Technologies Corporation
Note: Circuits shown are for example purposes only. You must carefully verify circuitry used in your application. 18

19. Energy Harvesting Additional Reading
Electrical Energy An Introduction 3rd Edition
Mohamed A. El-Sharkawi
The International System of Units (SI)
Catalog of Units 8th Edition, 2006
Piezoelectric Energy Harvesting Alper Erturk / Daniel Inman (Wiley 2011)
Materials, Preparation, and Characterization in Thermoelectrics, D.M. Rowe (CRC 2012) 19