Patent ID: 8217532

Claim:
A real time clock driving circuit for driving a real time clock, comprising: a power source coupled to a power input of the real time clock; a flash driving circuit comprising a booster, a charging capacitor, and a plurality of first resistor dividers, the booster comprising an input and an output, the input being coupled to the power source, the anode of the charging capacitor being coupled to the output of the booster, the cathode of the charging capacitor being grounded, the first resistor dividers being coupled in series between the output of the booster and the ground; and a switch circuit comprising a MOS transistor and a second resistor divider, the source of the MOS transistor coupled to a node between two of the first resistor dividers, the gate of the MOS transistor coupled to the node via the second resistor divider, and the drain of the MOS transistor coupled to the power input of the real time clock.