Post by thread:Extreme cold temperature

Anyone have any experience running a pic down to -60 degrees C? I tried a simple experiment with an externally clock driven PIC16c73 running a PWM output, all by itself. My can of envirotech chiller spray, which says -62 F, killed the PWM output and so, I presume, the whole chip. I haven't yet characterized it accurately below -40 C. I need a PWM output and a UART, although I could easily emulate them. Also an ADC would be nice but not necessary at that temperature. Is there a temperature range for any Microchip controller below -40 C? It would seem that some of the lads driving cars in Iceland would appreciate them.

At 8:43 AM 11/11/96, Paul Bjork wrote: >Anyone have any experience running a pic down to -60 degrees C? I >tried a simple experiment with an externally clock driven PIC16c73 >running a PWM output, all by itself. My can of envirotech chiller >spray, which says -62 F, killed the PWM output and so, I presume, the >whole chip. I haven't yet characterized it accurately below -40 C. > >I need a PWM output and a UART, although I could easily emulate them. >Also an ADC would be nice but not necessary at that temperature. > >Is there a temperature range for any Microchip controller below -40 C? >It would seem that some of the lads driving cars in Iceland would >appreciate them. if you can spare the power, add a heater. There are several companies that sell little heater elements (basically resistors) about the size of large postage stamps that run on AC or DC. craig ________________________________________________________ Dr. Craig Hollabaugh Wireless Scientific, Inc. 1890 South 14th Street Building 100, Suite 105 Amelia Island, FL 32034 904 261 6977 904 261 2129 fax spam_OUTwsciTakeThisOuTnet-magic.net Or you might know me as Dr. Craig Hollabaugh Analog Microelectronics, Georgia Institute of Technology .....hollaKILLspam@spam@monique.adgrp.gatech.edu or Dr. Craig Hollabaugh Aerospace Department, University of Texas, Austin hollaKILLspamcfdlab.ae.utexas.edu

Paul Bjork wrote: > > Anyone have any experience running a pic down to -60 degrees C? I > tried a simple experiment with an externally clock driven PIC16c73 > running a PWM output, all by itself. My can of envirotech chiller > spray, which says -62 F, killed the PWM output and so, I presume, the > whole chip. I haven't yet characterized it accurately below -40 C. > > I need a PWM output and a UART, although I could easily emulate them. > Also an ADC would be nice but not necessary at that temperature. > > Is there a temperature range for any Microchip controller below -40 C? > It would seem that some of the lads driving cars in Iceland would > appreciate them. What usually happens with freeze mist is the consequent condensation causes significant leakage currents.......you need low humidity air to properly perform such a test. There are a variety of materials incompatibility issues that become serious problems below -40C, so regardless of electronic performance, I agree with suggestion to include a heater. The high positive tempco polymeric types are particularly easy to apply. -- Paul Mathews, consulting engineer AEngineering Co. .....optoengKILLspam.....whidbey.com non-contact sensing and optoelectronics specialists

IMHO :) The freeze-spray is a little misleading - condensation is a problem for sure - also the thrermal gradient is so large you will crack the die or pop wire bonds. If you cool the part slowly it may work. If you cool it quickly it'll crack. Jon Bertrand EraseMEjonbspam_OUTTakeThisOuTcirris.com