Wireless Temperature Sensor AMBIENT LIGHT EXTENDS BATTERY LIFE INDEFINITELY LIGHT SOLAR PANELS LTC®3330 ENERGY HARVESTER IC PRECISION 0.1°C TEMPERATURE MEASUREMENT ACCURACY ULTRALOW SELF-DISCHARGE BATTERY (ON BACK) HIGHLY RELIABLE SMARTMESH IP WIRELESS NETWORK The DC2126A is a high accuracy wireless temperature sensor, powered from ambient light, built using Linear Technology integrated circuits. A 24-bit delta-sigma ADC reads a thermistor biased from a precision voltage reference. A switching power supply harvests energy from the builtin solar panel, and automatically switches over to the internal battery when no ambient light is available. A SmartMesh IP™ wireless radio module provides the wireless mesh connectivity and communicates the temperature to a central access point (manager). DC2126A Components SOLAR PANEL BATTERY LTC3330 EH_ON GPIO WIRELESS NETWORK LDO_EN LDO_OUT 3.0V (DUTY CYCLE) VOUT 3.6V LTC6654-2.5 VSUPPLY LTP5901-IPM SPI LTC2484 THERMISTOR BRIDGE Figure 1. A Wireless temperature sensor is formed by connecting a wireless radio module to an ADC, reference and thermistor. The circuit is powered by an energy harvester that can take power from a battery or solar panel. L, LT, LTC, LTM, Linear Technology, the Linear logo, the Dust Networks logo, Dust Networks, Eterna, Manager-on-Chip, and SmartMesh are registered trademarks and Easy Drive, LTP, Mote-on-Chip, and SmartMesh IP are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. DC2126A Components Part Number Function Benefits LTC2484 24-Bit Delta-Sigma ADC, Reads Thermistor Easy Drive™ Inputs Allow Direct Hook-Up of Thermistor LT®6654 Low Noise Voltage Reference Bias Thermistor for Low Noise Reading of Temperature LTP 5901-IPM SmartMesh IP Mote PCB Module Automatically Forms Low Power, Reliable Wireless Mesh Network. Built-In Microprocessor Manages ADC and Power Supplies LTC3330 Energy Harvesting DC/DC Converter Prioritizes Between Solar Power and Battery Power ™ The DC2126A acts as a wireless node, or mote, in a SmartMesh IP network. Temperature readings are sent through the mesh network to a demonstration PC software GUI that displays temperature, and whether the DC2126A is running on solar power or on battery. DC2126A DC9000B SmartMesh IP STARTER KIT DC2126A RECEIVER EXAMPLE SOFTWARE GUI DC2126A Software Utilities ADDITIONAL REFERENCES Online Description of the DC2126A with documentation www.linear.com/demo/DC2126A Step By Step Instructions to Operate the DC2126A www.linear.com/docs/45351 Article Describing Theory of Operation of the DC2126A Circuit www.linear.com/docs/45098 Other SmartMesh IP Demo Boards www.linear.com/starterkits www.linear.com/dc2126a n 1-800-4-LINEAR 1014