Organic light-emitting display apparatus and method of driving the same

A method of driving an organic light-emitting display apparatus, the organic light-emitting display apparatus including a plurality of pixels,

• wherein a first level of a first power supply voltage supplied to the plurality of pixels is changed according to time, and a circuitry for generating the first power supply voltage includes a first transistor for pulling-up the first power supply voltage, a second transistor for pulling-down the first power supply voltage, and a first resistor connected to a gate of the second transistor and having a variable resistance, the method comprising:
• when a first control signal level of a first power supply voltage control signal supplied to the gate of the second transistor through the first resistor is changed so that the first power supply voltage is changed from a high voltage level to a low voltage level, detecting a second gate voltage applied to the gate of the second transistor;
• and
• if the second gate voltage applied to the gate of the second transistor exceeds a first reference voltage level, reducing a first resistance of the first resistor.