The HYM8563 is a CMOS real time clock/calendar，which provides seconds，minutes， hours，day，date，month， and year information。The number of days ineach month and leap years are automatically adjusted。The clock can operate in two modes： one is the 12-hour mode with an AM/PM indicator，the other is the 24-hour mode。 The clock/calendar is full binary-coded decimal (BCD)。In addition, the HYM8563 contains a programmable clock output，a timer， an alarm， a voltage-low detector。 All address and data are transferred serially via I2C bus and The HYM8563 operates as a slave device on the serial bus。 The built-in word address register is incremented automatically after each written or read data byte。 The HYM8563 is designed to operate on very low power consumption。