Abstract: A secondary-side protection and sense circuit for a power converter has a sensing component, an adder amplifying circuit, an electronic switch, and a charge/discharge circuit. The sensing component is connected to an output connecting terminal of the power converter. The adder amplifying circuit has an operational amplifier, a first resistor, and a second resistor. The operational amplifier has an input terminal connected to the sensing component, an output terminal connected to a primary-side control component, and a power terminal. The first resistor and the second resistor are connected in series and between the input terminal and the power terminal of the operational amplifier. The electronic switch is connected between a ground terminal and a connection node between the first resistor and the second resistor. The charge/discharge circuit is connected to the electronic switch and the power terminal of the operational amplifier.

Abstract: A self-driven active clamp circuit applied to a flyback converter having a transformer and a switch has a clamp switch and a resistor. The clamp switch is connected between a first capacitor and a second capacitor in series. Another terminal of the first capacitor is connected to a first terminal of a primary-side winding of the transformer. Another terminal of the second capacitor is connected to a second terminal of the primary-side winding of the transformer and the switch of the flyback converter. A terminal of the resistor is connected to a control terminal of the clamp switch. Another terminal of the resistor is connected to the second terminal of the primary-side winding of the transformer and the switch of the flyback converter.

Abstract: A self-driven active clamp circuit applied to a flyback converter having a transformer and a switch has a clamp switch and a resistor. The clamp switch is connected between a first capacitor and a second capacitor in series. Another terminal of the first capacitor is connected to a first terminal of a primary-side winding of the transformer. Another terminal of the second capacitor is connected to a second terminal of the primary-side winding of the transformer and the switch of the flyback converter. A terminal of the resistor is connected to a control terminal of the clamp switch. Another terminal of the resistor is connected to the second terminal of the primary-side winding of the transformer and the switch of the flyback converter.

Abstract: A multi-mode hybrid control DC-DC converting circuit has a switching power converter and a microcontroller. The switching power converter has a transformer and a switching switch. The switching switch is connected to a primary-side winding of the transformer in series. The microcontroller is connected to the switching power converter and a control terminal of the switching switch. The microcontroller sets multiple thresholds according to an input voltage of the switching power converter, and determines whether a feedback voltage of the switching power converter is higher or lower than each one of the thresholds to perform a variable-frequency mode, a constant-frequency mode, or a pulse-skipping mode. The microcontroller outputs a driving signal to the switching switch and correspondingly adjusts a frequency of the driving signal according to the variable-frequency mode, the constant-frequency mode, or the pulse-skipping mode which is performed.

Abstract: A wide input voltage range power converter circuit in a one-stage-two-switch configuration has a power input terminal, a switch node connected to the power input terminal, a transformer, two electronic switches, a pulse width modulation (PWM) circuit, and an output circuit. An input side of the transformer has a first winding and a second winding that are connected to the switch node. An output side of the transformer has an output winding. A turns ratio between the first winding and the output winding is different from a turns ratio between the second winding and the output winding. The two electronic switches are respectively connected to the first winding and the second winding in series. The PWM circuit is connected to the power input terminal and control terminals of the two electronic switches. The output circuit is connected to the output winding.

Abstract: An auxiliary power supply circuit operating within a wide input voltage range has a voltage follower unit and a voltage comparison unit. The voltage follower unit has an electronic switch, a resistor, and a Zener diode. The electronic switch has a first terminal electrically connected to a voltage input terminal of the working voltage conversion circuit, a second terminal electrically connected to a voltage output terminal of the working voltage conversion circuit, and a control terminal. The resistor is electrically connected between the first terminal and the control terminal of the electronic switch. The Zener diode has a cathode electrically connected to the control terminal of the electronic switch. The voltage comparison unit has a detecting terminal electrically connected to the voltage input terminal of the working voltage conversion circuit, and an output terminal electrically connected to the control terminal of the electronic switch.