Display apparatus, method of driving the display apparatus and display system including the display apparatus

A method of driving a display apparatus, the method comprising:

• outputting a panel driving signal to a display panel;
• determining a driving frequency of the display panel from the panel driving signal;
• generating a touch driving signal having a frequency synchronized with the driving frequency;
• and
• outputting the touch driving signal to a touch driving signal output layer of a touch panel.

A display system comprising:

• a display panel;
• a panel driver configured to output a panel driving signal to the display panel;
• a touch driving signal output layer of a touch panel;
• and
• a touch driver configured to determine a driving frequency based on the panel driving signal and output a touch driving signal to the touch driving signal output layer having a frequency synchronized to the driving frequency.