Em 10/10/2013 22:42, Xiaofan Chen escreveu: > On Fri, Oct 11, 2013 at 3:53 AM, shawn mulligan > wrote: >> Can anyone offer their personal experiences when dealing with PIC >> microcontrollers in high-temperature applications -- say, > 170C... >> Outside of the stated ranges. >> >> Specifically, is there a particular device that works for you? Do you >> consider thermal resistance in your design? Heat-sinking? PCB? > I do not know anything about this. But there are specialized > product which work at high temperature. > > http://www.halliburton.com/en-US/ps/sperry/drilling/measurement-while-dri= lling-mwd.page?node-id=3Dhfyjrqum > "Quasar PulseSM MWD/LWD Service > > Extend the reach of current MWD/LWD sensors rated to temperatures > of 175=B0C (347=B0F) to 200=B0C (392=B0F), providing reliable directional= data and > steering capabilities in the most extreme downhole environments." > > I heard that they use expensive components (eg: OpAMP, ADC, MCU, > DSP). On the other hand, the life span of some of the above product > will be quite short (< 1 hour). Perhaps the idea is "let's insulate it well and see how long it lasts". If you thermally insulate the sensitive parts of the device and add some thermal ballast (ice for instance), it may last a long time until the internal temperature rises to a damaging point. Perhaps if the time of dwell in the harsh environment is not too long, the device may survive to be used again. Isaac --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .