Abstract: An integrated circuit for a power supply circuit that generates an output voltage from an alternating current (AC) voltage, the power supply circuit including a transistor configured to control a current flowing through an inductor. The integrated circuit comprises: a first terminal, to which a first capacitor is coupled, that receives a voltage corresponding to the AC voltage; a driver circuit turns on the transistor in response to a predetermined condition being satisfied, and turns off the transistor based on a feedback voltage corresponding to the output voltage and the voltage corresponding to the AC voltage, an ON period of the transistor inversely correlating to a level of the voltage corresponding to the AC voltage; and a discharge circuit that discharges the first capacitor in a time period from a first timing at which the transistor is turned off to a second timing at which the transistor is turned on.

Abstract: A power supply circuit that generates an output voltage from an AC voltage inputted thereto. The power supply circuit includes a rectifier circuit rectifying the AC voltage, an inductor receiving a rectified voltage from the rectifier circuit, a transistor controlling an inductor current flowing through the inductor, and an integrated circuit switching the transistor based on the inductor current and the output voltage. The integrated circuit includes a sample-and-hold circuit that samples-and-holds a voltage corresponding to the rectified voltage in a predetermined timing, an output circuit that outputs a limit voltage based on the voltage held by the sample-and-hold circuit, indicating a limit value for limiting the inductor current, and a signal output circuit that receives the limit voltage and a voltage corresponding to the inductor current, to thereby output a signal to turn off the transistor upon determining that a current value of the inductor current exceeds the limit value.

Abstract: An integrated circuit for a power supply circuit of a resonant type, the power supply circuit including a resonant circuit including a coil and a capacitor coupled in series, and a switching device controlling a resonant current flowing through the resonant circuit. The integrated circuit is configured to drive the switching device, and includes: a terminal configured to receive a voltage corresponding to the resonant current; a first voltage output circuit configured to output a first voltage obtained by multiplying the voltage at the terminal by a first factor; a second voltage output circuit configured to output a second voltage obtained by multiplying the voltage at the terminal by a second factor smaller than the first factor; and a driver circuit configured to drive the switching device, based on the first and second voltages, and a feedback voltage corresponding to an output voltage of the power supply circuit.

Abstract: An integrated circuit for controlling switching of a transistor in a power supply circuit. The integrated circuit includes: a first detection circuit configured to detect whether an inductor current has reached a first predetermined value; a signal output circuit configured to operate in a first mode or a second mode; a control circuit configured to control the signal output circuit to operate in the first mode when an amplitude of the first voltage after the inductor current has reached the first predetermined value is smaller than a second predetermined value, and to operate in the first mode or the second mode, corresponding to a condition of a load of the power supply circuit, when the amplitude is larger than the second predetermined value; and a driver circuit configured to turn on and off the transistor based respectively on the signal and a feedback voltage corresponding to the output voltage.

Abstract: An integrated circuit for a power supply circuit. The integrated circuit includes an oscillator circuit configured to output an oscillator voltage that rises with a predetermined slope from a first voltage, upon an inductor current of the power supply circuit becoming smaller than a first predetermined value, an error voltage output circuit configured to output an error voltage corresponding to a difference between a reference voltage and a feedback voltage corresponding to the output voltage, a drive circuit configured to turn on and off a transistor of the power supply circuit respectively upon the inductor current becoming smaller than the first predetermined value, and upon the oscillator voltage reaching a second voltage that is based on the error voltage, and an output circuit configured to change the first and/or second voltage based on a rectified voltage obtained by full-wave rectification of the AC voltage, and to output the changed voltage.

Abstract: A power supply circuit having a first capacitor, a transformer including a primary coil having a voltage of the first capacitor applied thereto, a secondary coil and an auxiliary coil, a second capacitor having a voltage from the auxiliary coil applied thereto, a transistor controlling an inductor current flowing through the primary coil, a control circuit outputting a first control signal when supply of the input voltage is unstopped, or is stopped yet a voltage of the second capacitor reaches a first level, and outputting a second control signal thereafter when the voltage of the second capacitor further reaches a second level, a first drive circuit outputting a first drive signal for switching control of the transistor in response to the first control signal, and a second drive circuit outputting a second drive signal for controlling on-resistance of the transistor to discharge the first capacitor, in response to the second control signal.

Abstract: An integrated circuit for a power supply circuit that generates an output voltage from an input voltage and includes an inductor and a transistor, the integrated circuit configured to switch the transistor to control a current of the inductor. The integrated circuit includes a first terminal that receives a power supply voltage, a second terminal that receives a voltage corresponding to an operation state of the integrated circuit, a storage circuit, a switching circuit that switches an operation mode of the integrated circuit based on voltage levels at the first and second terminals, the operation mode including a write mode, a test mode and a normal mode, a memory control circuit that writes setting information into the storage circuit, when the integrated circuit operates in the write mode, and a setting target circuit that operates based on the setting information stored in the storage circuit, when the integrated circuit operates in the test mode.

Abstract: A power supply circuit includes an inductor, a power transistor configured to control an inductor current flowing through the inductor, and an integrated circuit driving the power transistor. The integrated circuit includes a first terminal that receives a power supply voltage for operating the integrated circuit, generated according to a variation in the inductor current, a second terminal to which a control electrode of the power transistor is coupled, a first drive circuit configured to drive the power transistor via the second terminal during a first time period to turn on the power transistor, and a second drive circuit configured to drive the power transistor via the second terminal during a second time period to turn on the power transistor, the second time period including at least a part of the first time period, driving capability of the second drive circuit being lower than that of the first drive circuit.

Abstract: An integrated circuit for a power supply circuit configured to generate an output voltage of a target level from an alternating current (AC) voltage. The power supply circuit includes a first capacitor and an inductor configured to receive a voltage according to the AC voltage, and a transistor configured to control an inductor current flowing through the inductor. The integrated circuit is configured to switch the transistor, and includes: an identification circuit configured to identify whether a voltage level of an effective value of the AC voltage is a first level or a second level, and a signal output circuit configured to output a driving signal to drive the transistor, and correct the driving signal to thereby correct the input current, in response to the voltage level of the effective value being the first level and the second level, respectively.

Abstract: An integrated circuit for a power supply circuit that includes a transistor and generates an output voltage of a target level. The integrated circuit is configured to switch the transistor. The integrated circuit includes a first terminal configured to receive a feedback voltage according to the output voltage, a signal detection circuit configured to detect, through the first terminal, a setting signal received from an external circuit that operates based on the output voltage, and a driver circuit configured to drive the transistor in response to the setting signal detected by the signal detection circuit.

Abstract: A signal output circuit including a first transistor coupled to a power supply line to receive a power supply voltage, a diode provided between the power supply line and a gate electrode of the first transistor, and a current generation circuit provided on a ground side with respect to the diode, the current generation circuit being configured to generate a current for the diode, upon turning on of the first transistor, and to increase the current, upon the power supply voltage dropping below a predetermined level.

Abstract: An integrated circuit for a power supply circuit. The integrated circuit includes an oscillator circuit configured to output an oscillator voltage that rises with a predetermined slope from a first voltage, upon an inductor current of the power supply circuit becoming smaller than a first predetermined value, an error voltage output circuit configured to output an error voltage corresponding to a difference between a reference voltage and a feedback voltage corresponding to the output voltage, a drive circuit configured to turn on and off a transistor of the power supply circuit respectively upon the inductor current becoming smaller than the first predetermined value, and upon the oscillator voltage reaching a second voltage that is based on the error voltage, and an output circuit configured to change the first and/or second voltage based on a rectified voltage obtained by full-wave rectification of the AC voltage, and to output the changed voltage.

Abstract: An integrated circuit for a power supply circuit that generates an output voltage from an input voltage and includes an inductor and a transistor, the integrated circuit configured to switch the transistor to control a current of the inductor. The integrated circuit includes a first terminal that receives a power supply voltage, a second terminal that receives a voltage corresponding to an operation state of the integrated circuit, a storage circuit, a switching circuit that switches an operation mode of the integrated circuit based on voltage levels at the first and second terminals, the operation mode including a write mode, a test mode and a normal mode, a memory control circuit that writes setting information into the storage circuit, when the integrated circuit operates in the write mode, and a setting target circuit that operates based on the setting information stored in the storage circuit, when the integrated circuit operates in the test mode.

Abstract: A power supply circuit includes an inductor, a power transistor configured to control an inductor current flowing through the inductor, and an integrated circuit driving the power transistor. The integrated circuit includes a first terminal that receives a power supply voltage for operating the integrated circuit, generated according to a variation in the inductor current, a second terminal to which a control electrode of the power transistor is coupled, a first drive circuit configured to drive the power transistor via the second terminal during a first time period to turn on the power transistor, and a second drive circuit configured to drive the power transistor via the second terminal during a second time period to turn on the power transistor, the second time period including at least a part of the first time period, driving capability of the second drive circuit being lower than that of the first drive circuit.

Abstract: An integrated circuit that drives a switching device provided between a first line on a ground side and a second line on a power supply side, when a power supply voltage is applied between a first input terminal connected with a first capacitor and a second input terminal, the first capacitor having one end grounded and another end connected to the first input terminal, the integrated circuit includes: a first terminal connected to a circuit element, the circuit element having one end grounded and another end connected to the first terminal; and a drive circuit that changes a voltage at the first terminal to one logic level when a drive signal of the switching device changes to the one logic level, and changes the voltage at the first terminal to another logic level when the drive signal changes to the other logic level.

Abstract: A power supply circuit that generates an output voltage from an AC voltage inputted thereto. The power supply circuit includes a rectifier circuit rectifying the AC voltage, an inductor receiving a rectified voltage from the rectifier circuit, a transistor controlling an inductor current flowing through the inductor, and an integrated circuit switching the transistor based on the inductor current and the output voltage. The integrated circuit includes a sample-and-hold circuit that samples-and-holds a voltage corresponding to the rectified voltage in a predetermined timing, an output circuit that outputs a limit voltage based on the voltage held by the sample-and-hold circuit, indicating a limit value for limiting the inductor current, and a signal output circuit that receives the limit voltage and a voltage corresponding to the inductor current, to thereby output a signal to turn off the transistor upon determining that a current value of the inductor current exceeds the limit value.

Abstract: A power supply circuit having a first capacitor, a transformer including a primary coil having a voltage of the first capacitor applied thereto, a secondary coil and an auxiliary coil, a second capacitor having a voltage from the auxiliary coil applied thereto, a transistor controlling an inductor current flowing through the primary coil, a control circuit outputting a first control signal when supply of the input voltage is unstopped, or is stopped yet a voltage of the second capacitor reaches a first level, and outputting a second control signal thereafter when the voltage of the second capacitor further reaches a second level, a first drive circuit outputting a first drive signal for switching control of the transistor in response to the first control signal, and a second drive circuit outputting a second drive signal for controlling on-resistance of the transistor to discharge the first capacitor, in response to the second control signal.

Abstract: A power factor improvement circuit that performs, on the basis of an output voltage when a switching power-supply apparatus is in a light-load state or a no-load state, a burst operation for switching between states of the switching operation of a switching element includes: a first circuit that outputs a first voltage that corresponds to the error between a reference voltage and a voltage obtained by dividing the output voltage; and a clamp circuit that, while the burst operation is performed, clamps the lower limit of the first voltage, which decreases when the switching operation of the switching element is disabled, at a lower-limit voltage higher than the ground voltage of the power factor improvement circuit and clamps the upper limit of the first voltage, which increases when the switching operation of the switching element is performed, at an upper-limit voltage.

Abstract: A driver circuit includes a gate capacitance discharge circuit that reduces a resistance value of a resistor for pulling down the gate of a PMOSFET at the output stage for a predetermined period at the timing when an NMOSFET turns on and a pull-down resistor switching circuit that switches pull-down resistors of the gate capacitance discharge circuit, based on a divided voltage into which voltage of the high voltage power supply system is divided, in which the pull-down resistor switching circuit, when the divided voltage is higher than a reference voltage Vref, switches the pull-down resistor for the predetermined period to a resistor and, when the divided voltage is the reference voltage Vref or lower, switches the pull-down resistor to a resistor having a higher resistance value than the resistor.

Abstract: A power factor improvement circuit that performs, on the basis of an output voltage when a switching power-supply apparatus is in a light-load state or a no-load state, a burst operation for switching between states of the switching operation of a switching element includes: a first circuit that outputs a first voltage that corresponds to the error between a reference voltage and a voltage obtained by dividing the output voltage; and a clamp circuit that, while the burst operation is performed, clamps the lower limit of the first voltage, which decreases when the switching operation of the switching element is disabled, at a lower-limit voltage higher than the ground voltage of the power factor improvement circuit and clamps the upper limit of the first voltage, which increases when the switching operation of the switching element is performed, at an upper-limit voltage.