A power transistor has a semiconductor body with a bottom side and top side spaced distant from the bottom side in a vertical direction. The semiconductor body includes a plurality of transistor cells, a source zone of a first conduction type, a body zone of a second conduction type, a drift zone of the first conduction type, a drain zone, and a temperature sensor diode having a pn-junction between an n-doped cathode zone and a p-doped anode zone. The power transistor also has a drain contact terminal on the top side, a source contact terminal on the bottom side, a gate contact terminal, and a temperature sense contact terminal on the top side. Depending on the first and second conduction types the anode or cathode zone is electrically connected to the source contact terminal and the other diode zone is electrically connected to the temperature sense contact terminal.