Patent ID: 8792946

Claim:
An electronic circuit, comprising: a micro controller unit; a timing-generation sensor operable to output a certain detection result; a buffer circuit which accepts an output of the timing-generation sensor; a logic circuit controlled by the output signal of the timing-generation sensor and an output 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 the buffer circuit, wherein the buffer circuit has a diode connected to an terminal thereof on a ground side, no protection diode connected to an input terminal thereof on the 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 standby and power-source cutoff states by the time that the timing-generation sensor outputs the certain detection result, and is restored from the one of the standby and power-source cutoff states to the active state according to an output from the buffer circuit, wherein the power-source cutoff state is not a same mode as the standby state, and a power supply from the power source to 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 supply from the power-source to the power supply terminals of the micro controller is maintained in the standby state and the state thereof transitions from the standby state to the active state by using a control signal connected to a terminal of the micro controller other than the power supply terminals thereof.