This paper proposes a method of Always-On Display (AOD) function, named H/W Efficient Standalone AOD that operates AOD function inside Display Driver IC (DDI) itself with Application Processor (AP) sleep mode for low-power operation. Moreover, this paper also proposes a novel AOD operating architecture that can remove the additional memory required to express AOD information. Through experimental results, the proposed method demonstrates that the power consumption is reduced by 17.6% effectively without costing additional memory or causing cognitive image quality loss compared to the conventional AOD method.