Patent ID: 8954778
Filing Date: 2015-02-10
Classification: G04G,G06F

Abstract:
1. An electronic timekeeping circuit comprising: a plurality of power supplies; and timekeeping circuit components that are grouped into a plurality of power supply domains, wherein power is supplied to each of the power supply domains exclusively by a corresponding one of the power supplies, wherein timekeeping registers are duplicated for each of the power supply domains, wherein a power-on signal is generated after an alternating current (AC) power supply for a first power supply domain is turned on and transmitted to timekeeping registers in a second power supply domain via a first level shifter to copy data stored in the timekeeping registers in the second power supply domain to timekeeping registers in the first power supply domain via a second level shifter, and wherein the timekeeping registers are synchronized between the power supply domains if one of the timekeeping registers is modified and a power supply that supplies power to the one of the timekeeping registers is turned off such that the timekeeping registers store same information.