BME280 Temperature Offset

[dmic_redlore]

We have a product we have designed where we incorporated the BME280.   We have paid attention to read and use the trim values in the chip and that seems to be working well, however, we have seen a temperature offset of around 1 to 3 deg in most of the devices.  Once this offset is corrected, the device seems to be accurate across a wide range of temprature (checking it against a NIST certified device).  My question is why do we have this offset since this should be taken care of with the factory calibration?

In terms of self heat, I do not believe this is an issue of self heat because the PCB temperature next to the device seems to be at ambient temperature.   To put things in perspective, ambient is 22, PCB temperature is 22 and sensor is reading 24.

If required I can provide the code used for reading the trim values and how they are incorporated in the temperature reading process.

Thanks

[BSTRobin]

Hello dmic_redlore,

What is your PCB layout? Are there any heating component on your PCB?

[dmic_redlore]

Hi BSTRobin,

The PCB has several components that could generate heat and we are aware of this however, in our analysis we made sure that all these devices are OFF.   In fact during analysis our background current was around 20uA at 3.6V.    I was also measuring the PCB temperature with an IR gun and that mathed the real ambient temperature so I do not believe this is a problem of PCB heat.   If required. I can do a video or photo report of my analysis.

Thanks

[BSTRobin]

Hello dmic_redlore,

As you have checked PCB board, could you check SW code you used. There was reference code in github for your reference. https://github.com/BoschSensortec/BME280_driver