INTEGRATED CIRCUIT AND POWER SUPPLY CIRCUIT

To provide an integrated circuit capable of appropriately controlling a power supply circuit irrespective of change in external state.SOLUTION: An integrated circuit drives a transistor of a power supply circuit, the power supply circuit generating a predetermined level of output voltage from an input voltage and including a transformer that includes a primary coil, a secondary coil, and an auxiliary coil and the transistor that controls a current flowing through the primary coil. The integrated circuit comprises: a first terminal to which a power supply voltage according to a voltage from the auxiliary coil is applied; a second terminal to which a feedback voltage according to the output voltage is applied; a third terminal to which a voltage according to a current flowing through the transistor when the transistor is in an on-state is applied; a first determination circuit that determines whether or not a detection circuit for detecting a voltage generated at the auxiliary coil is connected between the third terminal and the auxiliary coil on the basis of the voltage at the third terminal when the transistor is in an off-state; and a switching control circuit that controls switching of the transistor on the basis of the voltages at the second and third terminals and the determination result of the first determination circuit.SELECTED DRAWING: Figure 2 【課題】 外部状態の変化に関わらず、適切に電源回路を制御することができる集積回路を提供する。【解決手段】 集積回路は、１次コイル、２次コイル、及び補助コイルを含むトランスと、前記１次コイルに流れる電流を制御するトランジスタと、含み、入力電圧から所定レベルの出力電圧を生成する電源回路の前記トランジスタを駆動する集積回路であって、前記補助コイルからの電圧に応じた電源電圧が印加される第１端子と、前記出力電圧に応じた帰還電圧が印加される第２端子と、前記トランジスタがオンの際に前記トランジスタに流れる電流に応じた電圧が印加される第３端子と、前記トランジスタがオフの際の前記第３端子の電圧に基づいて、前記第３端子及び前記補助コイルの間に前記補助コイルに生じる電圧を検出するための検出回路が接続されているか否かを判定する第１判定回路と、前記第２及び第３端子の電圧と、前記第１判定回路の判定結果と、に基づいて、前記トランジスタのスイッチングを制御するスイッチング制御回路と、を備える。【選択図】 図２