Abstract: A detection circuit for a switching converter, whereby: the detection circuit is coupled in parallel with an output capacitor of the switching converter, and is configured to provide a detection branch coupled in parallel with the output capacitor during a first period of a switching cycle, in order to detect an output voltage of the switching converter; and an output voltage detection signal is generated according to the detected output voltage during a second period of the switching cycle. A switching converter can include the detection circuit and an integrated circuit.

Abstract: A dimming signal generation circuit configured for an LED driver can include: a voltage-type dimmer configured to generate a dimming voltage; a dimming control circuit comprising a transformer and a power switch coupled in series between a first voltage and ground; where a secondary side of the transformer is coupled to the voltage-type dimmer is configured to receive the dimming voltage; where a primary side of the transformer is configured to receive the first voltage; and where a dimming reference signal is generated at the primary side of the transformer in accordance with the dimming voltage.

Abstract: A control circuit for controlling an AC-DC power supply, can include: a pulse-width modulation (PWM) signal generating circuit configured to generate a PWM signal in accordance with a reference voltage and a current sampling signal representing an inductor current flowing through an inductor of the AC-DC power supply, and to control a power stage circuit of the AC-DC power supply in accordance with the PWM signal; and a reference voltage generating circuit configured to generate the reference voltage based on an input voltage of the AC-DC power supply.

Abstract: A dimming control circuit for an LED driver, can include: an adjusting circuit configured to generate an adjusting signal in accordance with a PWM dimming signal; and where a switching state of a power transistor of the LED driver is adjusted in accordance with the adjusting signal and a constant current control signal. A dimming control method for an LED driver, can include: determining a first threshold in accordance with a frequency of the PWM dimming signal and a frequency range of audio noise; generating an adjusting signal having a first duty cycle when a duty cycle of a PWM dimming signal is not greater than the first threshold; and controlling, by the adjusting signal, a switching state of a power transistor in the LED driver, where the first duty cycle is greater than the duty cycle of the PWM dimming signal.

Abstract: A leakage protection circuit can include: a pull-down current generation circuit coupled between output terminals of a rectifier circuit; and a control circuit configured to control the pull-down current generation circuit to generate a pull-down current during a predetermined time interval, and to determine whether leakage occurs in accordance with a voltage detection signal that is representative of an output voltage of the rectifier circuit.

Abstract: A method of reducing THD can include: acquiring a first average inductor current during a first conduction time of a main power transistor of a power converter in a switching cycle; acquiring a second average inductor current during a second conduction time and an off time of the main power transistor in the switching cycle; and adjusting the second conduction time of the main power transistor in accordance with a difference between the first and second average inductor currents, where the first and second conduction times are successive.

Abstract: An LED dimming control circuit can include: a detection circuit configured to receive a dimming control signal, and to generate a detection signal for characterizing a type of the dimming control signal; and a dimming signal generation circuit configured to generate a dimming signal according to the detection signal and the dimming control signal, where a duty cycle of the dimming signal corresponds to the dimming control signal. A dimming control method can include: receiving a dimming control signal; detecting a number of rising or falling edges of the dimming control signal within a period of time to generate a detection signal; and determining a type of the dimming control signal in accordance with the detection signal.

Abstract: A detection circuit for a switching converter, whereby: the detection circuit is coupled in parallel with an output capacitor of the switching converter, and is configured to provide a detection branch coupled in parallel with the output capacitor during a first period of a switching cycle, in order to detect an output voltage of the switching converter; and an output voltage detection signal is generated according to the detected output voltage during a second period of the switching cycle. A switching converter can include the detection circuit and an integrated circuit.

Abstract: A control circuit for controlling an AC-DC power supply, can include: a pulse-width modulation (PWM) signal generating circuit configured to generate a PWM signal in accordance with a reference voltage and a current sampling signal representing an inductor current flowing through an inductor of the AC-DC power supply, and to control a power stage circuit of the AC-DC power supply in accordance with the PWM signal; and a reference voltage generating circuit configured to generate the reference voltage based on an input voltage of the AC-DC power supply.

Abstract: A leakage protection circuit can include: a pull-down current generation circuit coupled between output terminals of a rectifier circuit; and a control circuit configured to control the pull-down current generation circuit to generate a pull-down current during a predetermined time interval, and to determine whether leakage occurs in accordance with a voltage detection signal that is representative of an output voltage of the rectifier circuit.

Abstract: A dimming signal generation circuit configured for an LED driver can include: a voltage-type dimmer configured to generate a dimming voltage; a dimming control circuit comprising a transformer and a power switch coupled in series between a first voltage and ground; where a secondary side of the transformer is coupled to the voltage-type dimmer is configured to receive the dimming voltage; where a primary side of the transformer is configured to receive the first voltage; and where a dimming reference signal is generated at the primary side of the transformer in accordance with the dimming voltage.

Abstract: An apparatus for an LED driver with a silicon-controlled dimmer, can include: a bleeder circuit coupled to a DC bus of the LED driver, and being configured to draw a bleeder current from the DC bus; and a controller configured to adjust the bleeder current to decrease in accordance with a first current sampling signal that represents a drive current flowing through an LED load after the silicon-controlled dimmer transitions from an off state to an on state. A method of controlling an LED driver can include: drawing a bleeder current from a DC bus of the LED driver; and controlling the bleeder current in accordance with a first current sampling signal representing a drive current flowing through an LED load to decrease after the silicon-controlled dimmer transitions from an off state to an on state.

Abstract: A method of reducing THD can include: acquiring a first average inductor current during a first conduction time of a main power transistor of a power converter in a switching cycle; acquiring a second average inductor current during a second conduction time and an off time of the main power transistor in the switching cycle; and adjusting the second conduction time of the main power transistor in accordance with a difference between the first and second average inductor currents, where the first and second conduction times are successive.

Abstract: An LED dimming control circuit can include: a detection circuit configured to receive a dimming control signal, and to generate a detection signal for characterizing a type of the dimming control signal; and a dimming signal generation circuit configured to generate a dimming signal according to the detection signal and the dimming control signal, where a duty cycle of the dimming signal corresponds to the dimming control signal. A dimming control method can include: receiving a dimming control signal; detecting a number of rising or falling edges of the dimming control signal within a period of time to generate a detection signal; and determining a type of the dimming control signal in accordance with the detection signal.

Abstract: A method of reducing THD can include: acquiring a first average inductor current during a first conduction time of a main power transistor of a power converter in a switching cycle; acquiring a second average inductor current during a second conduction time and an off time of the main power transistor in the switching cycle; and adjusting the second conduction time of the main power transistor in accordance with a difference between the first and second average inductor currents, where the first and second conduction times are successive.

Abstract: A dimming control circuit for an LED driver, can include: an adjusting circuit configured to generate an adjusting signal in accordance with a PWM dimming signal; and where a switching state of a power transistor of the LED driver is adjusted in accordance with the adjusting signal and a constant current control signal. A dimming control method for an LED driver, can include: determining a first threshold in accordance with a frequency of the PWM dimming signal and a frequency range of audio noise; generating an adjusting signal having a first duty cycle when a duty cycle of a PWM dimming signal is not greater than the first threshold; and controlling, by the adjusting signal, a switching state of a power transistor in the LED driver, where the first duty cycle is greater than the duty cycle of the PWM dimming signal.

Abstract: A method of controlling an LED driver can include: generating a sinusoidal half-wave signal having the same frequency and phase as an AC input voltage by utilizing a phase-locked loop; generating a sampling signal of a peak value of an inductor current in a power stage circuit of the LED driver; generating a loop compensation signal in accordance with the sinusoidal half wave signal and a signal representing an output current of the power stage circuit; and generating a switching control signal for controlling the power stage circuit in accordance with the sampling signal and the loop compensation signal.

Abstract: A method of reducing THD can include: acquiring a first average inductor current during a first conduction time of a main power transistor of a power converter in a switching cycle; acquiring a second average inductor current during a second conduction time and an off time of the main power transistor in the switching cycle; and adjusting the second conduction time of the main power transistor in accordance with a difference between the first and second average inductor currents, where the first and second conduction times are successive.

Abstract: A dimming signal conversion method can include: converting a dimming voltage to a PWM signal; adjusting a corresponding relationship between the dimming voltage and a duty cycle of the PWM signal according to brightness requirements of a LED light source; and generating a drive current of an LED driver based on the corresponding relationship.

Abstract: An apparatus for an LED driver with a silicon-controlled dimmer, can include: a bleeder circuit coupled to a DC bus of the LED driver, and being configured to draw a bleeder current from the DC bus; and a controller configured to adjust the bleeder current to decrease in accordance with a first current sampling signal that represents a drive current flowing through an LED load after the silicon-controlled dimmer transitions from an off state to an on state. A method of controlling an LED driver can include: drawing a bleeder current from a DC bus of the LED driver; and controlling the bleeder current in accordance with a first current sampling signal representing a drive current flowing through an LED load to decrease after the silicon-controlled dimmer transitions from an off state to an on state.