The ELM341 is a complete temperature measurement and control system in an 8 pin package. It automatically reverts to a very low power sleep mode between measurements, making it suitable for battery operation. This integrated circuit is designed to compare two resistances and drive an output pin depending on the relative value of each. Typically, one of the resistors will be an NTC thermistor, and the other one will be a temperature independent resistor (whether fixed or variable). When the magnitude of the resistance connected to pin 2 exceeds the value of the resistance connected to pin 3, the output pin will be driven to a high state. Hysteresis maintains the output in that state until the relative values differ by approximately 8% (or typically 2C for a 10K thermistor).