Power management device

A power management device, comprising:

• a first power conversion device configured to generate a first driving voltage and output the first driving voltage to a source driver for a display device;
• a second power conversion device configured to generate a second driving voltage and output the second driving voltage to the source driver;
• a third power conversion device configured to generate a third driving voltage and output the third driving voltage to the source driver, third driving being smaller than the first driving voltage and greater than the second driving voltage;
• and
• a control device configured to control the first power conversion device, the second power conversion device, and the third power conversion device,
• wherein the first driving voltage is changed in a range of positive voltage and the second driving voltage is changed in a range of negative voltage,
• wherein the control device is configured:
• to change the third driving voltage as a driving voltage at a point where a sum of a first power consumption due to the changed first driving voltage and a second power consumption due to the changed second driving voltage is the smallest,
• to change the first driving voltage and the second driving voltage based on the changed third driving voltage, and
• to control the first power conversion device, the second power conversion device, and the third power conversion device so that the changed first driving voltage, the changed second driving voltage, and the changed third driving voltage are output, respectively.