Patent ID: 8094032

Claim:
A voltage detecting circuit for detecting a voltage range of a power source, said voltage detecting circuit comprising: a micro controlling unit comprising a general input/output port for issuing a digital level signal to said micro controlling unit and a controlling input/output port for outputting a constant voltage; and a boost circuit electrically connected to said power source and said micro controlling unit for providing said constant voltage to said micro controlling unit; a first divider resistor electrically connected to said micro controlling unit, said power source and said boost circuit; and a second divider resistor connected to said first divider resistor in series and electrically connected to said controlling input/output port of said micro controlling unit, wherein a judgment voltage is obtained according to said first divider resistor, said second divider resistor, said constant voltage and a voltage of said power source, said digital level signal is issued by said general input/output port according to said judgment voltage, said voltage range of said power source is determined by said micro controlling unit according to a logic-level of said digital level signal, and an enabling signal is generated by said micro controlling unit in response to said digital level signal.