Is there a temperature sensor on Pine?

[g_t_j]

Update:
Yesterday I used my Pine to do a temperature test.
I noticed that:
-the temperature in "thermal" tab is "30.0°C" and it doesn't change whatever I do.
-the temperature in "sensor" tab changes every second from 45 (just started up) up to 55°C (apparently it change randomly).

Is it the same for you?

It's the same for me as well.
I suppose we disregard the thermal tab and just read what the sensor says.

I believe this is the normal range you mention, between 45 and 55 degrees C. It can climb over 70 degress when running demanding apps. 

I have found that heat sinks and cooling in general helps a lot with performance.