Power supply device and display device including the same

A power supply device, comprising:

• a switch unit including a first transistor disposed between an input terminal that receives input power and a first node, an inductor disposed between the first node and a ground, and a second transistor disposed between the first node and an output terminal that outputs output power;
• a switching controller configured to output a first control signal that controls the first transistor and a second control signal that controls the second transistor based on a control signal and a frequency signal received from a controller;
• and
• a mode selector configured to supply a second mode operation signal that converts from a first mode to a second mode in which at least one of a driving method, a switching frequency, and a slew rate of the first transistor and the second transistor is variable compared to the first mode to the controller,
• wherein the mode selector compares a voltage level of the input power with a preset start voltage level, and generates the second mode operation signal when the voltage level of the input power is greater than or equal to the start voltage level.