Patent ID: 7649422
Filing Date: 2010-01-19
Classification: G06F

Abstract:
1. A RTC IC, comprising: an adjustable low-power oscillator, for providing a standard clock, wherein the standard clock produces a frequency drift corresponding to a current operation voltage of the adjustable low-power oscillator; a real time counter, coupled to the adjustable low-power oscillator, for counting a first counting number according to the standard clock without the frequency drift so as to obtain a constant counting time, and producing a detection signal timely; and a control unit, coupled to the adjustable low-power oscillator and the real time counter, for detecting the current operation voltage of the adjustable low-power oscillator when the control unit receives the detection signal, and locating the standard clock without the frequency drift corresponding to the current operation voltage of the adjustable low-power oscillator in a lookup table to determine whether or not the frequency drift is produced by a current standard clock of the adjustable low-power oscillator, wherein if the frequency drift is produced by the current standard clock of the adjustable low-power oscillator, the control unit produces a first control signal or a second control signal correspondingly to make the current standard clock of the adjustable low-power oscillator become the standard clock without the frequency drift corresponding to the current operation voltage of the adjustable low-power oscillator, and the real time counter counts the first counting number so as to obtain the constant counting time accordingly, wherein the adjustable low-power oscillator comprises: