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I am shopping for a PIC micro-controller for use in an automotive application. I noticed that PICs are offered in both "industrial" and "extended" temperature ranges ([-40C to +85C] vs [-40 to +125]). I should use the extended version, but due to availability, I may be forced to use the industrial or do something else entirely.

In any case, I became confused when I looked at the datasheet and saw that there is no distinction made on the line where operating temperature is specified. Here is an excerpt from page 265 of the datasheet found here: http://ww1.microchip.com/downloads/en/DeviceDoc/39995d.pdf

operating temperature table

The subsequent tables all make the distinction as seen here:

enter image description here

Can anyone decipher the meaning of this temperature range? Are the two versions fabricated using the same process and the extended versions are simply qualified to a higher level? Should I be concerned that the industrial version of the chip will fail at higher rates between 85C and 125C?

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For this kind of IC, the are fabricated on the same process (thus same absolute max ratings and thermal characteristics) and the temperature grade that you buy has to do with the guaranteed test limits on Electrical Characteristics.

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  • \$\begingroup\$ That's what I gathered. So why the distinction? Why will they guarantee the test limits on the extended version to a higher temperature? \$\endgroup\$ – kjgregory Nov 25 '14 at 0:54
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    \$\begingroup\$ One reason is binning: they make a bunch, test them, then the ones they know will work over the extended range are sold as extended, and the ones where it is questionable they sell as industrial. \$\endgroup\$ – helloworld922 Nov 25 '14 at 1:17
  • \$\begingroup\$ So does it seem reasonable to assume that if I'm using them well within their limits, that the industrial ones should hold up in higher temperatures (realistically, I only expect them to see no more than 90C in most cases)? \$\endgroup\$ – kjgregory Nov 25 '14 at 1:40
  • \$\begingroup\$ Maybe.... but they are not guaranteed. In fact if the decive COULD operate within spec at the wider temperature range, it would have already been binned as the higher range. So you may want to do your own incomming QA test to make sure the part is OK for the temperature you will be operating at. \$\endgroup\$ – MarkU Nov 25 '14 at 2:17
  • \$\begingroup\$ There will be no guarantees. You will have a better chance of avoiding problems if you operate the chip conservatively, not at extremes of frequency and operating voltage when the temperature is out of spec. Most likely operation at high temperatures and frequency/voltage is inferred by the margins at a test temperature near 25C, but only the manufacturer knows how to interpret their tests. Malfunctions when exceeding operating limitations may be subtle, and not easily tested by casual checking. \$\endgroup\$ – Spehro Pefhany Nov 25 '14 at 2:49

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