An integrated circuit for a power supply circuit that includes a state-indicating circuit, which is a first or second circuit when the power supply circuit is of a non-isolated or isolated type, as the case may be. The integrated circuit including a voltage generation circuit that generates, at a first terminal, a voltage that is (1) lower than a first level, when the first circuit is coupled to the first terminal, (2) higher than a second level, when the second circuit is coupled to the first terminal, and (3) higher than the first level and lower than the second level, when no state-indicating circuit is coupled to the first terminal, and a determination circuit that determines that the power supply circuit is of the non-isolated or isolated type, when the voltage at the first terminal is lower or higher than the second level, as the case may be.