19th Sep 2007

I went to the power lab to test the temperature sensor. As the oven itself has some error, and it is generally used for heating up not for cooling down, I can only start from a relatively high temperature and test from that onwards. The range I tested is 28~40 degree, which is also the range I will be working with. For every reading, I tested by setting the oven temperature, and reading from oscilloscope of the temperature sensor feedback, and recording down two readings in order to get the average value for t1 and t2.

Oven Temp.(°c) Average t1 Average t2 Calculated Temp.
28 8.64 16.73 28.42498506
29 8.64 16.8 29.28571429
30 8.66 16.95 30.63421829
31 8.65 16.98 31.23085984
32 8.67 17.11 32.31151373
33 8.69 17.2 32.90697674
34 8.68 17.29 34.1902834
35 8.63 17.3 35.46242775
36 8.65 17.45 36.71919771
37 8.64 17.51 37.62707025
38 8.68 17.65 38.28611898
39 8.64 17.7 39.74576271
40 8.67 17.85 40.71428571
41 8.68 17.91 41.14182021
42 8.67 18.05 42.86703601

And I got the following graph of t1 and t2:

23818300.ff22b5.jpg

the shape of the curve t1 and t2 roughly matches that provided in the datasheet, but with a difference about 2ms in t1 and 3ms in t2. I doubt this is because in the datasheet it has this Rload = 10kohm, during my testing there is no load put for the sensor.

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