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ADT7420 problem

Question asked by talbp on Nov 8, 2017
Latest reply on Nov 8, 2017 by BrenS

We're using ADT7420 in one of our boards.
The chip is communicating properly, but the results it provides are clearly wrong (around 32C when the room is 24-25C).

 

Some additional details:

1. The chip is exposed to open air.

2. The conversion formula we're was tested in the evb and it works fine there (the difference between the evb reading and the reading of the sensor on our board is also clear from the raw bytes).

3. we're working in normal mode and 16 bits resolution (though we've also tried 1-shot mode and 13 bits resolution and had the exact same problem).

4. After power-up the sensor seems to provide reasonable reading; Then, it quickly ascends, until it reaches around 31-32C).

5. The relevant part of the schematics is attached.

 

Did anyone encounter such problems in the past?

Any theories on what can cause this and how we can solve it?

 

Thanks in advance!

Tal

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