Heating device having heating transistor unit

A heating device, comprising:

• a heating transistor unit;
• a temperature sensing unit, configured to sense an ambient temperature and accordingly output a temperature sensing voltage;
• a driving unit, coupled to the heating transistor unit and the temperature sensing unit, configured to drive the heating transistor unit to perform heating based on the temperature sensing voltage;
• an activating unit, coupled to the temperature sensing unit and configured to output an activating signal based on the temperature sensing voltage when a sensed temperature has risen to a preset temperature, wherein the heating device activates an electronic apparatus according to the activating signal;
• and
• a hysteresis unit, coupled between the temperature sensing unit and the driving unit, wherein the hysteresis unit outputs a first voltage based on the temperature sensing voltage to enable the driving unit when the sensed temperature has risen to a first temperature, and outputs a second voltage based on the temperature sensing voltage to disable the driving unit when the sensed temperature has dropped to a second temperature, wherein the first temperature is higher than the second temperature.