Abstract: A high-voltage device provides a constant current drained from a high voltage source to charge a filter capacitor, where a voltage level of the higher voltage source is higher than 90 volts. When the operation voltage of the filter capacitor exceeds a first predetermined value, the charging of the filter capacitor by the constant current is stopped. A feedback loop is then used to maintain the operating voltage at substantially a second predetermined value lower than the first one.

Abstract: A frequency-jittering apparatuses includes an oscillator and a frequency control circuit. The oscillator generates a signal. When the magnitude of the signal exceeds a magnitude of a reference signal, the oscillator operates substantially in a first state; and when the magnitude of the signal is lower than the magnitude of the reference signal, the oscillator operates substantially in a second state different from the first one. The frequency control circuit varies the reference signal to change the frequency of the signal output from the oscillator.

Abstract: A compensation circuit has a resistor, a switch and a compensation capacitor. The resistor and the switch are connected in series between a power node and a compensation node. The compensation capacitor is connected to the compensation node, whose voltage is responsive to the output power source. For a predetermined period of time after the voltage falls below a predetermined value, the switch is open and no current flows through the resistor from the power node to the compensation node.

Abstract: A method of controlling a power supply comprising a switch and an inductive device includes turning the switch on to energize the inductive device, detecting inductor current flowing through the inductive device to generate a current sensing signal, comparing a peak of the current sensing signal and a limiting signal to generate an adjustment value, and comparing the current sensing signal and the limiting signal. The switch is closed when the current sensing signal, the limiting signal, and the adjustment value are approximately in a specific relationship for approximately equalizing a next peak of the current sensing signal to the limiting signal to cancel signal delay influence.

Abstract: Control method and related controller, applicable to a power supply with a switch and an inductive device. The inductive current through the inductive device is sensed. An operating frequency of the switch is controlled to make an average of the inductive current substantially equal to a predetermined portion of the peak of the inductive current and to make the inductive device operated in continuous conduction mode.

Abstract: A switch controller for switching power supply is coupled to an auxiliary winding of the switching power supply through a detecting resistor. The switch controller provides a detecting current passing through the detecting resistor for keeping the voltage level of a detecting signal transmitted by the detecting resistor higher than a predetermined voltage. In this way, the switch controller can avoid the latch-up phenomenon caused by receiving the detecting signal of the negative voltage level. In addition, the switch controller can detect the magnitude of an input voltage of the switching power supply by means of the detecting current, and accordingly control the operation of the switching power supply.

Abstract: An embodiment provides a sampling circuit, which has a sampling capacitor and a voltage compensation circuit. The voltage compensation circuit has a reference capacitor and a compensation circuit. The sampling capacitor samples a voltage signal and memorizes the signal as a sampling signal. The reference capacitor memorizes a reference signal with a predetermined value. The compensation circuit changes the reference signal with a recovery amount to recover the reference signal to the predetermined value, and simultaneously changes the sampling signal with an adjustment amount.

Abstract: An embodiment provides a control method capable of controlling a switching-mode power supply to provide an output power source. The switching-mode power supply has a winding coupled to an input power source and controlled by a switch to be energized or de-energized. The maximum current peak through the winding is set to be a predetermined value. A discharge time of the winding in a switching cycle period is detected. The switching cycle period of the switch is controlled to keep the ratio of the discharge time to the switching cycle period as a constant.

Abstract: A frequency-jittering apparatuses includes an oscillator and a frequency control circuit. The oscillator generates a signal. When the magnitude of the signal exceeds a magnitude of a reference signal, the oscillator operates substantially in a first state; and when the magnitude of the signal is lower than the magnitude of the reference signal, the oscillator operates substantially in a second state different from the first one. The frequency control circuit varies the reference signal to change the frequency of the signal output from the oscillator.

Abstract: Current control method and apparatus are disclosed. A current limiter is coupled to a switch connected in series with an energy transfer element of a power supply. The current limiter detects a current flowing through the switch and, when the current exceeds a current limit signal, turns off the switch. A limit signal generator provides the current limit signal, detects the maximum current value of the current, and updates the current limit signal according to the maximum current value and an ideal current limit value.

Abstract: A clock signal generating circuit includes a main delay circuit and a variable delay circuit. The main delay circuit receives a feedback clock signal, and outputs an output clock signal after a first delay when receiving the feedback clock signal. The variable delay circuit receives the output clock signal, and updates the feedback clock signal after a second delay when receiving the output clock signal. The second delay is periodically varied and is shorter than the first delay.