说明：  实时时钟芯片是日常生活中应用最为广泛的消费类电子产品之一。它为人们提供精确的实时时间,或者为电子系统提供精确的时间基准,目前实时时钟芯片大多采用精度较高的晶体振荡器作为时钟源。有些时钟芯片为了在主电源掉电时，还可以工作，需要外加电池供电。
(Real-time clock chip is one of the most widely used consumer electronic products in daily life. It provides precise real-time time for people, or provides an accurate time benchmark for electronic systems. Currently, most real-time clock chips use high precision crystal oscillator as the clock source. Some clock chips work when the main power is switched off, requiring extra battery power.)