Usage of temperature sensor of nRF52 above 85°C

[Remo]

Hi

We use the nRF52832 together with other devices in a housing. Some of the other devices may produce quite a lot of heat. Therefore we wanted to use the temperature sensor of the nRF52832 to measure when 85°C is reached and then shutdown the whole device.

The temperature sensor is specified to at most 85°C and has an accuracy of +/- 5°C. Therefore it is possible that it is actual 90°C when we measure 85°C. How does the temperature sensor behave when it is above 85°C (we are aware of that it is recommended not to run the nRF52832 above 85°C)? Is just the accuracy decreased?

Kind regards

[ovrebekk]

Hi Remo

The simple, if embarrassing, answer is that we don't really know how the temperature sensor will behave outside the specified absolute ratings ;) We test the chip to make sure it meets the specification within the defined operating ranges, and once you go outside then it is hard to predict.

The likely result like you say is that it will be much less accurate, and I expect that the current consumption will be much higher.

To be safe you should probably set the cutoff limit at 80°C measured, to make sure that the actual temperature is not above 85°C. Alternatively you would have to run some calibration of the temperature sensor, but this is probably not practically doable if you are going into mass production, as every device would have to be individually calibrated.

Best regards
Torbjørn

[Remo]

Thank you.