I am using the BEM280 Pressure/Humidity sensor in an Industrial application and need to sense ambient temperatures and pressures down to -40C. Based on the datasheet I have a few questions with regards to the accuracy in which I can get measurements: 1. What is the type of device that is actually making the temperature measurement? For example, is it a junction diode which has been characterized for forward voltage drop or is it a thermistor type or other. Is this device tied to the metal frame, substrate? 2. Is there any information regarding self-heating of the BME280 itself? There seems to be general statements that it is heavily reliant on parts around the BME sensor heating it, but has the internal device been characterized based on its own power consumption alone? 3. Can the metal surface of the part be directly connected to a metal surface which has direct connection to outside ambient world for improved thermal conduction (assume we have a small hole cavity for the pressure and humidity sense hole). Will any pressure on the metal structure interfere with pressure measurements? 4. The temperature accuracy has been stated in the datasheet as target values and not guaranteed from -40V to 0C. Is there any additional test data that is available to quantify this accuracy? Can we quantify the expected accuracy change from manufacturing lot to lot? 5. Does light getting into the hole of the BME280 interfere with any temperature/pressure/humidity sense?
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