| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a real time clock(RTC) circuit capable of highly accurately correcting time by simple constitution without increasing current consumption and the size of equipment. SOLUTION: When power supply for the equipment is turned on, an operation control part 60 controls the operation of a reference oscillator 30 and a frequency error detector 40 and the detector 40 measures the frequency error of a reference clock generated by a clock oscillator 10 by using a highly accurate reference clock generated by the oscillator 30. The frequency error is always inputted to an oscillator 50 with a correcting function. The oscillator 50 cumulatively adds a fixed value previously set by a digital oscillator to be driven by a reference clock whose frequency is divided by a frequency divider 20 and the frequency error by data consisting of the number of bits corresponding to requested accuracy, generates a clock based on the most significant bit(MSB) of the cumulatively added result, and when the accumulation of the frequency error reaches the MSB, corrects the generated clock.</p> |
