ADXL367 temperature calculation methods

Question

I am DFAE in Japan. Our customer evaluates ADXL367 and reads temperature register at 26C. 
 Temp_H[7:0] is 0x21 and temp_L[7:0] is 0xCC. 
 Therefore temp code is 2163 at 26C. 
 25C offset is 25x54-2163=-759. 
 Adxl367.h at Github shows Temp = (RAW + OFFSET) * SCALE. 
 When OFFSET is 1185, Temp is (RAW + 1185) /54. 
 if OFFSET is -759, can Temp be calculated using (RAW -759) /54 ? 
 Best regards 
 N.Kokubo

MarioSM · Accepted Answer

Hi NKokubo131 , excuse the delay and any inconvenience, From my understanding of the sensor's operating principle, I think there may be a misinterpretation in your approach; The bias value of these devices is of little help considering its deviation... With this in mind, the best approach is to use the value read at the current ambient temperature as a reference and use it as the basis for obtaining relative temperature measurements. In other words, due to this miscalibration related to temperature, the raw measurements do not give absolute temperature values , but relative values that must be calculated taking into account, in this case, the 26 C 2163 reference. 
 Does this makes sense to you? Hope this helps, feel free to reach me if you want to discuss this matter further. Have a great one, Mario SM)

MarioSM · Answer

Hi again NKokubo131 thanks for your patience. 
 NKokubo131 said: When Bais average is 165 on datasheet , OFFSET is 1185. ( 1185 = 25x54-165) 
 That looks good in order to have a first estimation on which numbers the temperature sensor is going to throw. And taking 26x54 - 2163 would also be correct since we are comparing the actual read value at 26 &ordm;C and its expected value in order to calculate the actual sensor offset, this is a solid approach in general terms for any other part, but; The standard deviation of 428 LSB makes the average bias value of 165 LSB less meaningful for this first estimate than for other parts where the standard deviation is not listed, since the difference between devices is not as large. (2.6 times higher in this case). For this reason, I suggested taking an initial raw measurement as a bias value and calculate relative measurement on top of that, as described in the previous answer formula. Hope things are clear now, I am glad to help so let me know if I can try assist you any further. Mario SM

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ADXL367 temperature calculation methods