On Fri, Oct 11, 2013 at 10:33 AM, Isaac Marino Bavaresco wrote: > 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-dr= illing-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 directiona= l 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. Probably. On the other hand, what I heard is that they really use components which can withstand 200=B0C and thus the components are really expensive, 10s of dollars or 100s of dollars per chip... --=20 Xiaofan --=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 .