Role of RTC(Real Time Clock) in Embedded Devices

RTC is an IC(integrated circuit) device and also a computer clock that keep track of the current time. It assists to keep and maintain accurate time in devices.

It is powered by an internal lithium battery. As a result of which even if the power of the system is turned off, the RTC clock keeps running. Below picture is an anatomy of rtc IC and it has a tiny lithium battery.

RTC maintains its clock by counting the cycles of an oscillator — usually an external 32.768kHz crystal oscillator circuit, an internal capacitor-based oscillator, or even an embedded quartz crystal. Some can detect transitions and count the periodicity of an input that may be connected.

Many RTCs can detect this change-over and go into an ultra-low power state where they power down all circuitry except those essential for maintaining the clock in order to conserve battery life. RTCs can also include alarm functions — set times that when reached trigger the RTC to drive an output that wakes the processor up.

Data flow diagram of rtc time function

In general RTC ICs regulate time with the use of a crystal oscillator and do not rely on clock signals like most hardware clocks. Aside from…