Idle period frequency scaling to reduce dynamic power of display driver IC

The proportion of power consumption occupied by the display panel in the mobile device is increasing due to the driving the high frame rate and the increase in resolution. Among them, the power of the display driver IC (DDI), a core component that drives the display panel, was also increased. Recently, Variable Refresh Rate (VRR) technology has been widely used to reduce display panel power consumption, and to this end, DDI is also equipped with technology for VRR driving. During VRR operation, DDI can operate at a low frame rate, which is possible by extending the DDI idle period. During the idle period extension, dynamic power is still flowing because the clock is still toggling in the idle period. This paper introduces a frequency scaling technique through internal clock dividing in the idle period during the VRR operation. As a result of the frequency scaling we propose, at a sampling frame rate less than 60Hz, the power-saving effect of 8.82% on average and 11.11% on maximum can be confirmed through power simulation.