Hello. I use a kind of motion sensor located in a sealed metal enclosure. I perform temperature offset calibrating to this device, using an external temperature sensor (attached to the enclosure). This solves the most of temperature problems except when the temperature gradient is large - for instance for 1'st 5 minutes afrer powering the device. After checking this issue my conclusion was that in fast temperature gradients the temperature delta between the case temperature (Tcase, the one i measure) and internal (Tj) temperature is too large so i don't compensate the real offset error. My question is if there is a simple method to estimate the internal temperature (Tj), if at the beginning (before powering up the sensor) the external and internal temperatures are equal Tcase=Tj. Is there good information about it on the web? Thanx, Eli.