Energy Harvesting Reference Design

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Donald Gibbs
5 years ago
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1 Energy Harvesting Reference Design Sustainable, Ultra-Low-Power Solution for Wireless Sensor Node Applications Embargo Until May 25, 2011

Dramatic Growth Ahead in Energy Harvesting Energy harvesting device market is projected to grow exponentially

shipped in 2009 (Source: IDTechEx) No need for conventional batteries in many designs Batteries are not green

operating conditions Energy harvesting technology is environmentally friendly Natural energy resources are

harvesting and lowpower wireless technologies Energy harvesters have become cost-effective and efficient

2 Dramatic Growth Ahead in Energy Harvesting Energy harvesting device market is projected to grow exponentially this decade 10B+ energy harvesting devices forecast to ship by 2019 a 20x increase over ~500 million units that shipped in 2009 (Source: IDTechEx) No need for conventional batteries in many designs Batteries are not green must be recycled, often end up in landfills Costly and inconvenient to replace Unreliable under certain operating conditions Energy harvesting technology is environmentally friendly Natural energy resources are inexhaustible Conventional energy generation produces greenhouse gases We ve reached a tipping point in energy harvesting and lowpower wireless technologies Energy harvesters have become cost-effective and efficient Ultra-low power wireless MCUs can now operate at power levels low enough to implement wireless sensor nodes using harvested energy 2

Silicon Labs Energy Harvesting Wireless Solution Comprehensive Energy Harvesting Reference Design Wireless sensor node Wireless USB adapter Wireless sensor network GUI Solar-powered design Measures

3 Silicon Labs Energy Harvesting Wireless Solution Comprehensive Energy Harvesting Reference Design Wireless sensor node Wireless USB adapter Wireless sensor network GUI Solar-powered design Measures temperature, light level and charge level Single-chip Si1012 wireless MCU Transmits data to wireless USB adapter Connects wireless sensor node to PC MCU runs HID USB software as well as EZMac wireless network stack Optimized RF & USB implementation Displays data from wireless sensor node No special software drivers required 3

Turnkey Wireless Sensor Node Design Complete energy harvesting wireless sensor solution Includes all wireless network and USB software All circuit design including RF layout available Optimized for

4 Turnkey Wireless Sensor Node Design Complete energy harvesting wireless sensor solution Includes all wireless network and USB software All circuit design including RF layout available Optimized for ultra-low power consumption Uses Silicon Labs single-chip Si10xx wireless MCU for control and connectivity Most power-efficient wireless MCU available 20 na in deep-sleep mode and 2 microsecond wake-up time Reduces average system current through smart power cycling 4

5 Based on Industry s Lowest Power Wireless MCU Si10xx family extends battery life Lowest active current saves energy when device is running Lowest sleep current saves energy when device is inactive Industry s leading RF performance Up to +20 dbm output power without the need for external PA -121 dbm receive sensitivity greatly increases range Integrated dc-dc switching regulator extends input voltage range 0.9V to 3.6V operation 5

6 Operating Modes and Power Consumption LP sleep mode of the wireless MCU consumes 65 na and uses the pin port match to wake up (2 µs) The wireless MCU in RTC sleep and the RF transciever in standby is 350 na na, respectively Voltage regulator and associated circuitry consumes 3 µa of leakage current No Sleep Button Press? RTC on Yes Wake-up every 1s Transmit light level Send temp & charge level every 60s In Sleep mode, ENERGY-HARVEST-RD consumes ~ 3uA (leakage from battery management chips) In RTC mode, ENERGY-HARVEST-RD consumes ~ 3.8uA (MCU RTC adds 800nA to existing leakage) In Active mode, ENERGY-HARVEST-RD consumes ~ 51uA average current (3uA of this is battery management leakage) Active mode turns on the MCU and the RF transceiver 29 ma for transmit current at +13 dbm Yes RTC on for 3 minutes? No 19 ma receive current at -121 dbm sensitivity 6

Charging Times for Thin Film Battery Time to fully charge an empty battery with no system load Electric Light 50 200

7 Charging Times for Thin Film Battery Time to fully charge an empty battery with no system load Electric Light Lux Office Window 1000 Lux Direct Sunlight 100K Lux USB Charging Limited to 3 ma 24 hours 6 hours 2 hrs 30 minutes 7

8 Alternative Harvested Energy Sources The reference design can be powered by different sources of harvested energy RF, vibration (piezoelectric) and thermal sources RF Energy Solar cell Vibration Battery Management circuit Thin film battery Auxiliary Input Thermal ENERGY-HARVEST-RD 8

9 Minimal Bill of Materials = Low System Cost Wireless Sensor Board Wireless USB Adapter Debug connector Front Si1012 Wireless MCU Solar Cell Back Printed Antenna Thin Film Battery Si4431 RF IC Running EZMac Software C8051F342 USB MCU Running HID Firmware 9

10 Emerging Energy Harvesting Applications Wireless sensor nodes Home and building automation Industrial control systems Medical monitoring systems Infrastructure sensing systems Security systems Agricultural monitoring systems Asset tracking systems 10

Summary Market interest in energy harvesting solutions is large and growing Silicon Labs turnkey energy harvesting reference design for wireless sensor nodes speeds time to market Wireless networking

11 Summary Market interest in energy harvesting solutions is large and growing Silicon Labs turnkey energy harvesting reference design for wireless sensor nodes speeds time to market Wireless networking and USB software included in design Low bill of materials (BOM) Complete circuit design with RF layout Schematics and Gerber files Silicon Labs offers the lowest power wireless sensor node solution powered by harvested energy 11

Let s first take a look at power consumption and its relationship to voltage and frequency. The equation for power consumption of the MCU as it

Let s first take a look at power consumption and its relationship to voltage and frequency. The equation for power consumption of the MCU as it 1 The C8051F91x/0x product family is designed to dramatically increase battery lifetime which is the number one requirement for most battery powered applications. The C8051F91x has the industry s lowest