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We are currently designing a "conditioning" module that takes a couple of sensors (T°, Pressure but also via digital bus) and repeats over CAN / also outputs them in nice and clean analog signals (0-5V) when needed.

Problem is : we are trying to find an analog (the detail is imporant) thermocouple conditioning chip that carries a serious Cold Junction Compensation mechanism.

N.B : we've obviously found the AD595/59x series but they only specify (and guarantee, we've contacted them) for Cold Junction Temperatures above freezing point (0°C). They might work below but we have no firsthand experience with them out of the datasheet so we can't legitimately integrate them.

The other option being to use a Tk-to-digital but we want to avoid that for various reasons.

  • Is our only option to use discrete Op-Amps with a CJC mechanism based on discretes?
  • Have any of you any experience on using these integrated-CJC out of specs? the +50°C is fine by us but we need to go below 0°C. What we are really asking ourselves is : what happens when we go below the minimum (0°) ? Does the CJC stop working altogether or does it compensate based on a temperature of 0°?

Thanks for the help,

M

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  • \$\begingroup\$ Can you not warm the chip? It does operate below 0C. Performance is just not specified \$\endgroup\$ – DKNguyen Aug 27 '19 at 14:41
  • \$\begingroup\$ Nope, not a possibility. The application is a vehicle... \$\endgroup\$ – VoltsAndNuts Aug 27 '19 at 14:47
  • \$\begingroup\$ Vehicle...as in a fuel vehicle with a hot engine? \$\endgroup\$ – DKNguyen Aug 27 '19 at 14:48
  • \$\begingroup\$ You can use opamp and digital sensor for CJC. There are also thermocouple ADC converters with built-in CJC sensor. \$\endgroup\$ – Marko Buršič Aug 27 '19 at 14:48
  • \$\begingroup\$ "The other option being to use a Tk-to-digital but we want to avoid that for various reasons", can you elaborate those reasons? Are you projecting an analog or digital device? \$\endgroup\$ – Marko Buršič Aug 27 '19 at 14:55

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