Patent ID: 8326243

Claim:
An electronic circuit comprising: a micro controller unit; a timer operable to measure a standby time under control of the micro controller unit; a buffer circuit operable to receive an output signal of the timer; a logic circuit controlled by the output signal of the timer and an output signal of the micro controller unit; and a power-on switch controlled by the logic circuit in switching, and operable to supply a power source to the micro controller unit and buffer circuit, wherein the buffer circuit has a diode connected to an input terminal thereof on a ground side, no protection diode connected with an input terminal thereof on a power-source side, and has an input tolerant property, and the micro controller unit is made to transition from an active state thereof to one of a standby state and a power-source cutoff state during the standby time, and restored from the respective one of the standby state and the power-source cutoff state to the active state according to an output from the buffer, wherein the power-source cutoff state is not same mode as the standby state, and power supplied from the power source to one or more power supply terminals of the micro controller is stopped by switching off the power-on switch in the power-source cutoff state, and wherein power supplied from the power-source to the power supply terminals of the micro controller is maintained in the standby state and the micro controller transitions from the standby state to the active state according to a control signal connected to a terminal of the micro controller other than the power supply terminals thereof.