Power supply device and display device including the same

1. 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,

wherein the mode selector compares the voltage level of the input power with a preset end voltage level, which is different from the preset start voltage level, and stops the second mode operation signal when the voltage level of the input power is less than or equal to the preset end voltage level.

2. The power supply device of claim 1 , wherein the input power has a positive voltage level, and has a battery voltage range and an adapter voltage range greater than the battery voltage range.

3. The power supply device of claim 2 , wherein the battery voltage range is about 5.5V to about 17.6V, and the adapter voltage range is about 18V to about 22V.

4. The power supply device of claim 2 , wherein the mode selector does not generate the second mode operation signal in the battery voltage range.

5. The power supply device of claim 1 , wherein the start voltage level is greater than the preset end voltage level.

6. The power supply device of claim 1 , wherein the mode selector generates the second mode operation signal after a first buffer period when the voltage level of the input power is greater than or equal to the start voltage level, and stops the second mode operation signal after a second buffer period when the voltage level of the input power is less than or equal to the preset end voltage level.

7. The power supply device of claim 6 , wherein the first buffer period is shorter than the second buffer period.

8. The power supply device of claim 1 , wherein the mode selector further compares a voltage level of the output power with a voltage level corresponding to a preset output power signal, and generates the second mode operation signal when the voltage level of the output power is less than or equal to the voltage level corresponding to the preset output power signal.

9. The power supply device of claim 8 , wherein the output power has a negative voltage level.

10. The power supply device of claim 1 , wherein the controller comprises:

an interface unit configured to receive a register value that controls the switching controller;

a frequency generation circuit configured to generate the frequency signal using a reference clock signal; and

an output power controller configured to provide an output power signal to the mode selector.

11. The power supply device of claim 1 , wherein the switch unit is driven by any one of a first driving method of alternately turning on the first and second transistors in the first mode, a second driving method of alternately turning on the first and second transistors in a first period and simultaneously turning off the first and second transistors in a second period, and a third driving method of alternately turning on the first and second transistors in a (1-1)-th period and simultaneously turning off the first and second transistors in a (2-1)-th period longer than the second period.

12. The power supply device of claim 11 , wherein the switch unit is driven by the second driving method or the third driving method in the second mode.

13. The power supply device of claim 11 , wherein a turn-on breakdown voltage of the first transistor is a sum of a forwarding voltage, a maximum voltage of the input power, a minimum voltage of the output power, and an over transient voltage in the first driving method, and is a sum of the maximum voltage of the input power and the over transient voltage in the second and third driving methods.

14. The power supply device of claim 1 , wherein the switch unit sets the switching frequency as a reference frequency in the first mode and sets the switching frequency as a frequency lower than the reference frequency in the second mode.

15. The power supply device of claim 1 , wherein the switch unit controls the first and second transistors with a first slew rate in the first mode, and controls the first and second transistors with a second slew rate lower than the first slew rate in the second mode.

16. The power supply device of claim 15 , wherein a turn-off breakdown voltage of the first transistor is a sum of a maximum voltage of the input power, a minimum voltage of the output power, a forwarding voltage, and an under transient voltage, and a turn-off breakdown voltage of the second transistor is a sum of the maximum voltage of the input power, the minimum voltage of the output power, and an over transient voltage.

17. The power supply device of claim 16 , wherein a magnitude of an absolute value of the under transient voltage and the over transient voltage when the switch unit controls the first and second transistors with the second slew rate is lower than the magnitude of the absolute value of the under transient voltage and the over transient voltage when the switch unit controls the first and second transistors with the first slew rate.

18. A display device, comprising:

a display panel including a plurality of scan lines, a first power line, a second power line, and a plurality of pixels connected to the scan lines and the first and second power lines;

a scan driver configured to sequentially provide a plurality of scan signals to the scan lines; and

a power supply configured to convert input power into a first power voltage and a second power voltage, supply the first power voltage to the first power line, and supply the second power voltage to the second power line,

wherein the power supply comprises a mode selector that compares a voltage level of the input power with a preset start voltage level, and generates a mode operation signal that converts a first mode to a second mode when the voltage level of the input power is greater than or equal to the start voltage level,

wherein the mode selector further compares the voltage level of the input power with a preset end voltage level, which is different from the preset start voltage level, and stops the mode operation signal when the voltage level of the input power is less than or equal to the preset end voltage level,

wherein, in the second mode, at least one of a driving method, a switching frequency, and a slew rate of a first transistor and a second transistor included in the power supply is variable compared to the first mode.

19. The display device of claim 18 , wherein the power supply further comprises:

a switch unit including the first transistor disposed between an input terminal that receives the input power and a first node, an inductor disposed between the first node and a ground, and the second transistor disposed between the first node and an output terminal that outputs output power; and

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.