Research And Design Of A Real Time Clock Chip With Embeded Power Management

Real Time Clock plays a very important role in variety of application system. It provides a exact time reference, implements timekeeping or delay-control, works as a counter and stamp event in the system. As a RTC should work uninterruptedly, a Battey-Backup mechanism is usually equipped to make sure the time is go on when the main power supply is off.In this thesis a RTC chip used in consumptive electronics & industrial control field was designed. The low-power consumption chip uses I2C 2-wire bus as its interface and works as timekeeper, calendar, alarmer and trickle charger. Except the basic RTC, it has integrated a power management sub-system. This system can supervise the main power and switch the backup power(battery) to the RTC when main supply is off; at the same time, the access from the bus to internal registers is stoped to prevent the timing data. When the backup power is working, the RTC entres the mode of ultra low-power; while the system power is on again, the chip comes back to work ordinarily.As the whole chip has only 8 pins, it is very applicable in the low power consumptive electronics field.This chip is a Mixed-signal IC. In the whole design, we use a"top-down"design method combined with a"down-top"design method. In our project, the logic and spice simulation of every module and the whole system have finished correctly. And the whole layout design and verification was accomplished subsequently. These measurements assured correct design of our chip. The last design result completed accord with the design specification.