Touch screen controller, touch screen system including the touch screen controller, and method of operating the touch screen controller

1. A touch screen controller comprising:

a driving circuit configured to output a first driving signal in a first touch mode and a second driving signal in a second touch mode, the first touch mode including a driving period and a subsequent sensing period; and

a boosting circuit configured, in the first touch mode, to generate a first voltage by performing an internal switching operation based on an input voltage and a first switching signal, and configured to provide the first voltage to the driving circuit,

wherein the first switching signal has a first frequency in the driving period and a second frequency different from the first frequency in the subsequent sensing period.

2. The touch screen controller of claim 1 , wherein the first touch mode is a pen touch mode and the second touch mode is a finger touch mode.

3. The touch screen controller of claim 1 , wherein the second frequency is less than the first frequency or is 0.

4. The touch screen controller of claim 1 , wherein, in the second touch mode, the boosting circuit is further configured to generate a second voltage based on the input voltage and a second switching signal having a third frequency, and

wherein the third frequency has a value obtained by dividing the first frequency by N, where N is an integer equal to or greater than 2.

5. The touch screen controller of claim 4 , wherein the boosting circuit comprises a frequency modulator configured to generate the first switching signal in the first touch mode and the second switching signal in the second touch mode.

6. The touch screen controller of claim 1 , wherein, in the second touch mode, the driving circuit is configured to output the second driving signal based on a second voltage generated from outside the touch screen controller.

7. The touch screen controller of claim 1 , further comprising:

an analog front end circuit including a filter configured to filter a sensing signal received from a touch panel according to a pass band, the analog front end circuit configured to process the sensing signal in the second touch mode,

wherein a frequency of switching noise generated by an internal switching operation based on the second frequency in the boosting circuit is located outside the pass band of the filter.

8. The touch screen controller of claim 1 , wherein the touch screen controller is implemented using a single semiconductor chip into which the driving circuit and the boosting circuit are integrated.

9. The touch screen controller of claim 1 , wherein the boosting circuit includes a direct current (DC)-to-DC converter configured to generate the first voltage by boosting the input voltage.

10. A touch screen controller comprising:

a driving circuit configured to output a first driving signal to a touch panel in a pen touch mode including a driving period and a subsequent sensing period;

a boosting circuit configured, in the pen touch mode, to generate a first voltage by performing an internal switching operation based on an input voltage and a first switching signal, and configured to provide the first voltage to the driving circuit;

a first analog front end circuit configured to receive a first sensing signal generated due to a pen touch in the subsequent sensing period of the pen touch mode and process the first sensing signal; and

a control circuit configured to generate a control signal for controlling the internal switching operation of the boosting circuit,

wherein the control circuit is configured to interrupt the internal switching operation in the subsequent sensing period.

11. The touch screen controller of claim 10 , wherein the first switching signal has a first frequency in the driving period and a second frequency different from the first frequency in the subsequent sensing period.

12. The touch screen controller of claim 10 , wherein, in a finger touch mode:

the driving circuit outputs a second driving signal to the touch panel,

the touch screen controller comprises a second analog front end circuit configured to receive a second sensing signal generated due to a finger touch and process the second sensing signal, and

the boosting circuit generates a second voltage based on the input voltage and a second switching signal having a third frequency different from the first frequency and the second frequency, and provides the second voltage to the driving circuit.

13. The touch screen controller of claim 12 , wherein the third frequency is less than the first frequency.

14. The touch screen controller of claim 13 , wherein the third frequency has a value obtained by dividing the first frequency by N, where N is an integer equal to or greater than 2.

15. The touch screen controller of claim 12 , wherein the boosting circuit comprises a frequency modulator configured to generate the first switching signal in the pen touch mode and the second switching signal in the finger touch mode.

16. The touch screen controller of claim 10 , further comprising:

a display driving block configured to drive a display panel, and

wherein the display driving block comprises a timing controller configured to generate timing information related to display timing.

17. A method of operating a touch screen controller, the method comprising:

generating a first voltage by performing an internal switching operation based on a first switching signal, in a pen sensing mode including a driving period and a subsequent sensing period;

providing a first driving signal generated according to the first voltage to a touch panel;

generating a second voltage different from the first voltage by performing the internal switching operation based on a second switching signal, in a finger sensing mode; and

providing a second driving signal generated according to the second voltage to the touch panel,

wherein the first switching signal has a first frequency during the driving period and a second frequency different from the first frequency during the subsequent sensing period, and

wherein the second switching signal has a third frequency different from the first frequency.

18. The method of claim 17 , wherein the second frequency is less than the first frequency or is 0, and

wherein the third frequency has a value obtained by dividing the first frequency by N, where N is an integer equal to or greater than 2.

19. The method of claim 17 , wherein the performing of the internal switching operation in the subsequent sensing period of the pen sensing mode includes interrupting the internal switching operation by the first switching signal.

20. The method of claim 17 , wherein the first voltage is greater than the second voltage.