Power management circuit and display device having the same

A power management circuit comprising:

• a switching regulator for supplying a power to an external device in a discontinuous conduction mode or in a continuous conduction mode;
• and
• a sensing circuit for sensing whether the switching regulator is operated in the discontinuous conduction mode,
• wherein the switching regulator comprises:
• a comparator for receiving the supplied power to feedback the supplied power;
• and
• an RS latch for receiving an output signal from the comparator as a reset signal, and
• wherein the sensing circuit comprises:
• a phase lock loop circuit for generating a first clock signal;
• a phase delay circuit for receiving the first clock signal, and for generating a second clock signal having a phase delayed from a phase of the first clock signal;
• a first D flip-flop for receiving an output signal from the RS latch and the first clock signal, and operating at a rising edge;
• a second D flip-flop for receiving an output signal from the first D flip-flop and the first clock signal, and for operating at a falling edge;
• a third D flip-flop for receiving the output signal from the RS latch and the second clock signal, and for operating at a rising edge;
• a fourth D flip-flop for receiving an output signal from the third D flip-flop and the first clock signal, and for operating at a falling edge;
• an exclusive OR circuit for receiving an output signal from the second D flip-flop and an output signal from the fourth D flip-flop;
• a fifth D flip-flop for receiving an output signal from the exclusive OR circuit and a third clock signal having a frequency that is lower than a frequency of the first clock signal;
• a plurality of registers for sequentially storing signals output from the fifth D flip-flop;
• and
• a control circuit for controlling the phase delay circuit based on data stored in the registers.

A display device comprising:

• a display panel;
• and
• a power management circuit comprising a switching regulator for supplying a power to the display panel in a discontinuous conduction mode or in a continuous conduction mode, and a sensing circuit for sensing whether the switching regulator is operated in the discontinuous conduction mode,
• wherein the switching regulator comprises:
• a comparator for receiving and monitoring the supplied power;
• and
• an RS latch for receiving an output signal from the comparator as a reset signal, and
• wherein the sensing circuit comprises:
• a phase lock loop circuit for generating a first clock signal;
• a phase delay circuit for receiving the first clock signal, and for generating a second clock signal having a phase delayed from a phase of the first clock signal;
• and
• a determination circuit for receiving the first clock signal, the second clock signal, and an output signal from the RS latch, for outputting a first value when a pulse width of the output signal from the RS latch is smaller than a reference value, and for outputting a second value, which is different from the first value, when the pulse width of the output signal from the RS latch is greater than the reference value.