Patent ID: 6975313

Claim:
A power supply circuit for a display unit that transmits a power supply voltage to a display panel having pixels that are turned on when the power supply voltage is energized and that are turned off when the power supply voltage is non-energized, the power supply circuit comprising: a calculation circuit to calculate a total number of pixels that are turned on in the display panel; a voltage generation circuit to make the output impedance of a power supply voltage variable and to transmit the power supply voltage to the display panel; a control circuit to control the output impedance of the voltage generation circuit so that the output impedance becomes lower as the total number of pixels calculated by the calculation circuit increases; a clock-signal oscillator to generate a clock signal to control the voltage generation circuit; and a clock-control circuit to (a) divide generated clock signals into a plurality of systems, (b) determine to which of a plurality of split domains values of the clock signals correspond in accordance with a calculation in the calculation circuit, and (c) at least one of assert or de-assert the output of each of the clock signals that are divided into the plurality of systems, wherein the output impedance of the power supply voltage is controlled in accordance with the output of each of the clock signals.