Linear Technology Corporation Tony ArmstrongDirector of Product Marketing - Power Products
Energy Harvesting - Opportunity 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 installations and building HVAC Harvesting otherwise wasted heat from industrial processes, solar panels, internal combustion engines, etc. Various consumer electronic accessory chargers
Energy Harvesting Sources Thermo-Electric Generator or Thermopile (Heat) Piezo-Electric (Vibration or strain) PhotoVoltaic (Light) Galvanic (Moisture) Coil/Magnet (Motion)
LTC3108: Ultra-Low Voltage (20mV) Step-Up converter and Power Manager Operates from inputs as low as 20mV Selectable Fixed Output Voltages Unique Resonant Power converter / Energy Harvester Auxiliary LDO Manages Energy storage between Reservoir and Main Cout or Batt Compact Step-up X-former 3x4mm DFN or GN16 packages Transformer: Coilcraft LPR-6235 Design: Dave Salerno
LTC3108: Energy Harvesting Applications Remote Industrial Sensor networks HVAC monitoring and control Building Automation Predictive Maintenance Avionics Automatic Metering Power Conversion and Energy Management is the Missing Link “Free” Energy Source Energy Harvester / Manager Sensors, A/D, UController Wireless transmitter / receiver LTC3108 TEG, PV, Piezo, Electrochemical, trees…
LTC3108 Block Diagram Review 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
LTC3108 Feature: 20mV Resonant Boost Topology 20mV Operation or ~1deg dT if powered from a Peltier Effect Thermal Electric Generator (TEG or TEC) LTC proprietary compound Depletion mode N-Channel MOSFET makes extreme low voltage possible Circuit Self-oscillates, resonant circuit formed by Lmag and Cg Built-in Synchronous rectification improves Energy harvesting “yield” 1:100 transformer is standard Coilcraft part (LPR-6235), 6mm x 6mm x 3.5mm
LTC3108: Typical Performance Key Points: Average Power for the App, must be 10s of mWs or less… Higher Sample Rates = Higher dT or better TEG required Best Performance is obtained with lowest Rs TECs/TEGs LTC3108: Typical Performance Data
LTC3108: More Typical Performance Data Key Points: Bigger Area TEG = More mV per delta T, but also more ESR Small dT – Use 1:100 transformer Large dT – Use 1:50 or 1:20 or lower turns ratio transformers
LTC3108: TEG / TEG Reference Data Remember: Bigger TEG doesn’t always mean more available power!
LTC3108: Indoor Light Powered PhotoVoltaic Charger ~200 to 300mV available from small Solar Cells with Indoor lighting Battery or Storage Capacitor on output is trickle charged 1:20 transformer maximizes power delivery (charging current) • Potential Applications: • Autonomous Proximity Sensors • Battery-less Smoke/Gas detectors
LTC3108: Demo Circuit – DC1582A Rev.B will use the 3x4mm DFN package.
LTC3108: Schedule Datasheet: Now First Samples: Now Demo Boards: Now Product Release Date: December 1, 2009