MDBT42Q Built in thermometer

Hi,

Is this sensor good enough for recording the room temperature every 15 min without requiring particularly high precision, but it should not drift too much when the voltage drops.

It should be fine, yes. It won't drift, however you need to calibrate it first.

• So just measure the temperature with a device you trust, lets say it's 20 degrees C.
  
• Run var calib = 20 - E.getTemperature();
  
• Then whenever you read the temperature just do E.getTemperature()-calib
  
  

You only need to do that once per device. Otherwise it's fine.

Does the chip heat up too much to record the room temperature?

No, it should be fine in normal use. If you're doing BLE scanning or heavy calculation then maybe, but for doing something like recording room temperature you're good.

Or do I need something like a DS1820... Has the board enough power to drive this sensor?

You can use the DS18B20 with the MDBT42Q, but I don't think you need to. As above, the inbuilt one is probably fine