Semiconductor device

A semiconductor device comprising:

• a transmission circuitry which converts a first signal based on an input signal into a second signal and transmits the second signal;
• a reception circuitry which is electrically insulated from the transmission circuitry, receives the second signal, and outputs a third signal;
• a comparison circuitry which compares a reference voltage and a comparison object signal being one of the input signal and the third signal, and outputs a fourth signal which shifts when the comparison object signal shifts to a state of being higher than a first voltage from a state of being lower than the first voltage or when the comparison object signal shifts to a state of being lower than the first voltage from a state of being higher than the first voltage;
• a timer circuitry which outputs a fifth signal based on the fourth signal;
• and
• a switch circuitry which switches and outputs the reference voltage being one of the first voltage, a second voltage, and a third voltage, based on the fifth signal, the second voltage being lower than the first voltage, the third voltage being higher than the first voltage,
• wherein the timer circuitry continuously outputs the fifth signal:
• for a period from a first time when the comparison object signal shifts from the state of being lower than the first voltage to the state of being higher than the first voltage to a second time after a first predetermined time from the first time;
• and
• for a period from a third time when the comparison object signal shifts from the state of being higher than the first voltage to the state of being lower than the first voltage to a fourth time after a second predetermined time from the third time.