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A deviation between two ADT7320 chips

Question asked by xubing on Oct 20, 2017
Latest reply on Nov 9, 2017 by xubing

Hi, everyone!

 

I have a question about the temperature sensor, ADT7320.

In my project, I have to simultaneously measure the ambient air temperature and the PCB temperature. When designning the PCB, I followed the suggestions from AN-892. Two ADT7320 chips (on one PCB board) were used for measuring the ambient air temperature and the PCB temperature, respectively. The result is as follows:

 

 

As is shown, there's a deviation of about 0.4 centi-degree during the period of 10 minutes. What caused this deviation? I think this is probably due to the difference between the two internal voltage references in the two temperature sensors, since the two sensors do not share one common power supply (5V). Of cause, they have a common ground.

 

Thanks very much!

Best regards!

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