MLX90247B

MLX90247B Thermopile w/On-Chip Thermistor Features and Benefits Solid state sensor High reliability Low cost, small size On chip temperature sensor Applications Non-Contact Temperature Sensing Differential Temperature Sensing Climate Control Ear, Temple Thermometers Household and Commercial Appliances Ordering Information Part No. MLX90247B Description Thermopile with On-chip PTC Thermistor Functional Diagram Description The MLX90247B is a thermopile sensor IC which detects very small amounts of heat radiation. The sensor consists of a membrane with a thermopile on top of it. The hot junctions of the thermopile are positioned near the center of the membrane, the cold junctions above the bulk silicon edge. Due to the low thermal conductivity of the membrane, absorbed heat will cause the temperature to increase more at the center of the membrane than at the edge above the bulk. This temperature difference is converted to an electric potential by the thermo-electric effect in the thermopile junctions. No supply voltage is needed. ϑ+ The sensor IC is integrated together with a PTC thermistor in one silicon mass. The PTC is adjacent to the cold junctions of the thermopile. As such, use of the PTC is considered the more accurate method of measuring thermopile cold junction temperature, and thus overall sensor accuracy when making noncontact temperature measurement. The sensor and thermistor can be used independent of each other if desired, as the thermopile potential is floating. MLX90247B Discrete Infrared Sensor IC Page 1 Rev 1.0 17/Feb/01 MLX90247B Thermopile w/On-Chip Thermistor MLX90247B Electrical Specifications DC Operating Parameters TA = -40 C to 150 C, (unless otherwise specified) o o Parameter Thermopile Resistance Sensitivity TC of Sensitivity Time constant Thermistor Value Thermal Coefficient PTC (1) Symbol Rtp S TCs T Rptc A1 A2 Test Condition @298K sensor @298K black body @299K @298K @298K 25°C-100°C 2 Min 44 29 Typ 59.5 42 0.1 Max 75 55 30 33.8 8580 Unit kΩ µV/K %/K ms kΩ ppm/K ppm/K2 18.2 5720 26 7150 11.57 (1) R(T)=R(298K).[1+A1.(T-298K)+A2.(T-298) ] Note: when measuring resistances with an ohm meter, please take care that the internal protection diodes, as indicated in the diagram below, are always reverse biased. ϑ+ MLX90247B Absolute Maximum Ratings Parameter Operating temperature Storage temperature Soldering temperature Value -40 ~ 150 -40 ~ 150