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BMP280 measures with an 10hPa offset

Hi,

We've used the BMP280 sensor for some time and it has worked fine.

We received part delivery of a batch from our manufacturer this week and during verification we found that all 80 of these consistently measures a too low pressure. The offset is 10hPa.

This is very similar to another post (see link below), but in our case VDDIO is tied to VDD. As in that post, we are reading some strange calibration values. I have listed these below.

The software and hardware is the same for the previous 50 that works and these 80 that consistently measures with an offset. The configuration is 

  • 2x oversampling (temp and pressure)
  • Normal measurement mode
  • 0.5 ms timeout
  • No filter
  • Disabled 3-wire SPI

Another thing we have noticied is that the marking on the sensor differ from previous batches we have received. An example from a previous batch was "2DT-KS". On this batch it is "DRL-KL". I'm a little surpised by the last letter.

Coeff.Not workingWorkingT12778527350T22618125922T35050P13751638823P2-10541-10584P330243024P476386850P5-21-176P6-7-7P7724115500P8-5018-14600P9-7666000

 

Question 1: What does the "Sub-con ID" on the marking signify and does "L" mean it is not the "new variant"? If so, what does that imply?

Question 2: Any input on these strange coefficients?

Best reply by FAE_CA1

Hi,

Thanks for your inquiry.

According to BMP280 datasheet, the laser marking of "2DT KS" is the right laser marking for BMP280. The letter "K" stands for BMP280 and the letter "S" stands for BMP280 with underfill 0273300436. We don't have any BMP280 that has laser marking of "xxx KL", while we used to have old version of BMP280 parts with marking of "xxx KU" and "xxx KP", etc. The Sub-con ID "S", "U" and "P" are Bosch internal tracking letter.

From the calibration parameters point of view P5, P7, P8 and P9 of the wrong BMP280 parts are too far away from the working BMP280 parts. So most likely you purchased BMP280 parts from somewhere that is not our authorized distributors.

Thanks.

 

 

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