Real-time clock

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A real-time clock (RTC) is a computer clock (most often in the form of an integrated circuit chip) that keeps track of the current time even when the computer is turned off. It is used in many kinds of computers, and is present in all modern personal computers. RTCs are also present in many embedded systems.

Some models of integrated Real-time clock circuits are the DS1307 from Maxim and the PCF8563 from Philips.

Real-time clocks run on a battery that is not connected to the normal power supply. In contrast, clocks that are not real-time do not function when the computer is off.

RTC should not be confused with real-time computing. It also shouldn't be confused with CPU clock (The CPU clock regulates the execution of instructions.).

[edit] External links

• Power Considerations for Accurate Real-Time Clocks
• Selecting a Backup Source for Real-Time Clocks