VL6180x Accuracy Issue.

[Vignesh]

Hi Experts and Technical support,

We have manufactured 1000 boards with VL6180XV0NR/1 to measure proximity range of 20mm to 80mm. We tested all the boards individually for functionality and accuracy with X-rite white balance card of ~12cm square. Around 800 boards were good and measurements were within tolerance level consistently. But 200 sensors show either 5mm or 10mm offset on + & - side. Surprisingly, the offset is constant for any given sensor in this 200.

Now, my questions are:

    Is this offset variation across sensors expected?

    If yes, is there a way to store an identification in sensor to make the application program to apply ID-based offset?

    If no, is there anything we have to take care in manufacturing or using?

Thanks in advance for solution/tips.

Vignesh.

[John E KVAM]

The offset is caused by very slight changes to the chip during the re-flow process.

Good news is that there is an offset calibration section in the datasheet that covers this case.

You can either use the calibration code in the VL6180 API and store the result in your NVM to send to the sensor during the next reboot, or you can do the compensation yourself.

Either way, the offset is fixed and permanent. So once you determine it, you can store it and account for it during the life of the product.

• john