Maxim has a temperature sensor node running off 3.2mA
A reference design for a temperature measurement node from Maxim Integrated incorporates a current loop-powered transmitter for low power operation.
Intended for the measurement of temperature in industrial process control applications, the reference design called Novato transmits temperature measurements from remote sensors to the central control unit over a 4–20mA current-loop using the highway addressable remote transducer (HART) communication protocol.
The transmitter is designed to work with a Renesas RL78/G13 microcontroller.
The transmitter makes temperature measurement from -200 °C to +850 °C with accuracy better than ±0.1% or ±1.0 °C. Its power consumption is less than 3.2mA
Sensor inputs can be 2-, 3-, or 4-wire resistance temperature detectors types PT100 to PT1000.