I'm trying to figure out why my MAX31855 thermocouple converter appears to be outputting inaccurate temperature data. I'm curious if this is due to non-linearity in the converter. Link to data sheet: https://datasheets.maximintegrated.com/en/ds/MAX31855.pdf
The accuracy of the thermocouple seems to be okay around room temperature, however, it it becomes very inaccurate at higher temperatures. Around the 400-500F range, it can be off by +80F.
I'm somewhat familiar with the physics of thermocouples, but I'm definitely not an expert.
So my question: does the MAX31855 actually output accurate temperatures? The data sheet states that it outputs in units of 0.25 deg C. From this, I assumed that it would output accurate temperature data since it's using deg C as units.
However, I'm curious if this is a bad assumption. The FAQs page of the MAX31855 states that it does not linearize the results (link to FAQ page: https://www.maximintegrated.com/en/support/faqs/max31855-faq.html). This confuses me, why would it the datasheet say it outputs in units of 0.25 deg C if it's not actually linearized/valid?
Am I required to post-process the data by myself to get accurate temperature values?