What is the accuracy of stm32f070 internal temperature sensor?

[JKSah]

Hello,

As per page number 17 of datasheet of STM32F070 series we can see that it consists of internal temperature sensor. It's written that with calibration we can get quite accurate value of the temperature but can it be used as replacement of any external temperature sensor such as STTS751. Our application is based on logging of temperature in cold chain storage unit and in similar areas.

My question is that can we use this internal temperature sensor for this type of purpose or not hence reducing external temperature sensor? Can it provide that good accuracy as external sensor or not?

[Andreas Bolsch]

It measures the die temperature, not ambient temperatur. The difference between these two depends on your device as a whole (PCB layout, orientation, convection, enclosure etc.) and on the power dissipation of the F070 itself. If it is in one of the power save modes most of the time and there are no other circuit elements generating extra heating nearby, they should be pretty close to each other. However, even e.g. driving a LED constantly might cause significant self-heating. If you need *bullet-proof* and precise documentation of ambient temperature, the internal sensor is certainly not the proper choice.

[JKSah]

Okay, we will use external sensor then.​

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Thank you​

[TDK]

That information is in the datasheet.

You could calibrate it to get better accuracy, but it's generally not going to be as accurate as an external dedicated temperature sensor IC, which are cheap. And it measures the die temperature, not ambient, as Andreas Bolsch points out.