Display device and driving method thereof

A display device, comprising:

• a display panel having a sub-pixel, the display panel, in operation, displaying images in units of frames, each frame including active time followed by blank time;
• a reference voltage line associated with the sub-pixel;
• a data driver including:
• driving circuitry that, in operation, outputs a data voltage to a data line coupled to the sub-pixel;
• and
• sensing circuitry that, in operation, generates sensing data by sampling an electrical signal on the reference voltage line during a third period in which the reference voltage line is electrically floating;
• a power controller that, in operation, generates a first reference voltage during the active time and generates a second reference voltage during the blank time;
• and
• a timing controller that, in operation, detects a defect of the display panel based on the sensing data.