At the heart of the MLX90247 thermopile sensors is a silicon die with a central micromachined membrane surrounded by a bulk silicon edge. The hot junctions of the thermopile are positioned near the center of the membrane and the cold junctions are located above the bulk silicon edge. Infrared irradiation of the low thermal conductivity membrane creates a temperature difference between the membrane and the surrounding bulk silicon. The resulting thermopile voltage is a function of the temperature difference between the object and the sensor.
Measurement of the absolute temperature of the object is possible by relating the thermopile signal to the temperature of the sensor. The exact temperature of the sensor is measured by a PTC thermistor integrated in the bulk silicon edge. No supply voltage is needed for the
thermopile. The sensor and thermistor can be used independently of each other if desired, as the thermopile potential is floating.

Features and Benefits
*Solid state thermopile sensor
*On-chip thermistor for ambient temperature compensation
*High reliability and long-term stability
*Low cost, small size

*Automotive contactless temperature sensing.
*IR thermometers
*Gas analysis equipment
*Occupancy detection

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