Bosch Sensortec Community

    cancel
    Showing results for 
    Search instead for 
    Did you mean: 
    SOLVED

    BME280 Temperature Accuracy

    JDF1980
    New Poster

    BME280 Temperature Accuracy

    I am using the BEM280 Pressure/Humidity sensor in an Industrial application and need to sense ambient temperatures and pressures down to -40C. Based on the datasheet I have a few questions with regards to the accuracy in which I can get measurements:

    1. What is the type of device that is actually making the temperature measurement? For example, is it a junction diode which has been characterized for forward voltage drop or is it a thermistor type or other. Is this device tied to the metal frame, substrate?

    2. Is there any information regarding self-heating of the BME280 itself? There seems to be general statements that it is heavily reliant on parts around the BME sensor heating it, but has the internal device been characterized based on its own power consumption alone?

    3.  Can the metal surface of the part be directly connected to a metal surface which has direct connection to outside ambient world for improved thermal conduction (assume we have a small hole cavity for the pressure and humidity sense hole). Will any pressure on the metal structure interfere with pressure measurements?

    4. The temperature accuracy has been stated in the datasheet as target values and not guaranteed from -40V to 0C. Is there any additional test data that is available to quantify this accuracy? Can we quantify the expected accuracy change from manufacturing lot to lot?

    5. Does light getting into the hole of the BME280 interfere with any temperature/pressure/humidity sense?

    3 REPLIES 3
    handytech
    Community Moderator

    Re: BME280 Temperature Accuracy


    @JDF1980 wrote:

    1. What is the type of device that is actually making the temperature measurement? For example, is it a junction diode which has been characterized for forward voltage drop or is it a thermistor type or other. Is this device tied to the metal frame, substrate?


    Temperature is measured by the voltage change in a silicon diode. It is not tied to the metal frame.


    @JDF1980 wrote:

    2. Is there any information regarding self-heating of the BME280 itself? There seems to be general statements that it is heavily reliant on parts around the BME sensor heating it, but has the internal device been characterized based on its own power consumption alone?


    The BME280 is so sensitive that as you mentioned it can measure external influences, for instance from other components on the PCB if not considered carefully. The influence of its own power consumption is not significant enough to impact measurements.


    @JDF1980 wrote:

    3.  Can the metal surface of the part be directly connected to a metal surface which has direct connection to outside ambient world for improved thermal conduction (assume we have a small hole cavity for the pressure and humidity sense hole). Will any pressure on the metal structure interfere with pressure measurements?


    This is not recommended as indeed stress on the lid/package will impact the sensor's performance/accuracy.


    @JDF1980 wrote:

    4. The temperature accuracy has been stated in the datasheet as target values and not guaranteed from -40V to 0C. Is there any additional test data that is available to quantify this accuracy? Can we quantify the expected accuracy change from manufacturing lot to lot?


    The sensor is optimized for best performance in the range from 0°C to 65°C, and therefore full accuracy in specified in this range as well. If not specified, we unfortunately cannot provide more data than in the datasheet.


    @JDF1980 wrote:

    5. Does light getting into the hole of the BME280 interfere with any temperature/pressure/humidity sense?


    Light can influence the accuracy of the measurements (photocurrent of silicon), therefore it is recommended to avoid exposure to strong light sources.

    JDF1980
    New Poster

    Re: BME280 Temperature Accuracy

    Thank you for the information. I have one more follow-up question.

    6. The BME280 has specific compensation values for temp/humidity/pressure. Is each BME280 specifically calibrated for temp accuracy at either a specific ambient temperature or temp range? Or are the comp values generated based upon a more global analysis and applied across multiple BME280 batches? 

    Thank you. 

    handytech
    Community Moderator

    Re: BME280 Temperature Accuracy

    Each BME280 are individually calibrated during production and there is no generic rule across batches, therefore one should use the trimming values from the sensor's register map directly.

    Icon--AD-black-48x48Icon--address-consumer-data-black-48x48Icon--appointment-black-48x48Icon--back-left-black-48x48Icon--calendar-black-48x48Icon--center-alignedIcon--Checkbox-checkIcon--clock-black-48x48Icon--close-black-48x48Icon--compare-black-48x48Icon--confirmation-black-48x48Icon--dealer-details-black-48x48Icon--delete-black-48x48Icon--delivery-black-48x48Icon--down-black-48x48Icon--download-black-48x48Ic-OverlayAlertIcon--externallink-black-48x48Icon-Filledforward-right_adjustedIcon--grid-view-black-48x48IC_gd_Check-Circle170821_Icons_Community170823_Bosch_Icons170823_Bosch_Icons170821_Icons_CommunityIC-logout170821_Icons_Community170825_Bosch_Icons170821_Icons_CommunityIC-shopping-cart2170821_Icons_CommunityIC-upIC_UserIcon--imageIcon--info-i-black-48x48Icon--left-alignedIcon--Less-minimize-black-48x48Icon-FilledIcon--List-Check-grennIcon--List-Check-blackIcon--List-Cross-blackIcon--list-view-mobile-black-48x48Icon--list-view-black-48x48Icon--More-Maximize-black-48x48Icon--my-product-black-48x48Icon--newsletter-black-48x48Icon--payment-black-48x48Icon--print-black-48x48Icon--promotion-black-48x48Icon--registration-black-48x48Icon--Reset-black-48x48Icon--right-alignedshare-circle1Icon--share-black-48x48Icon--shopping-bag-black-48x48Icon-shopping-cartIcon--start-play-black-48x48Icon--store-locator-black-48x48Ic-OverlayAlertIcon--summary-black-48x48tumblrIcon-FilledvineIc-OverlayAlertwhishlist