Abstract: A flyback power converter circuit converting an input voltage to an output voltage includes a transformer, a power switch, a synchronous rectifier (SR) switch, and a secondary side control circuit. The secondary side control circuit controls the SR switch to be ON when the power switch is OFF. The secondary side control circuit includes a driving switch for controlling the SR switch, a synchronous control circuit powered by a voltage related to the output voltage, which controls the driving switch to operate the SR switch, and a clamping circuit including a clamping switch and a clamping switch control circuit. The clamping switch control circuit controls the clamping switch according to a current inflow terminal voltage of the clamping switch and/or the voltage related to the output voltage, such that, during a secondary side power-on period, an equivalent impedance of the current inflow terminal of the clamping switch is smaller than a predetermined clamping impedance.

Abstract: A flyback power converter circuit converting an input voltage to an output voltage includes a transformer, a power switch, a synchronous rectifier (SR) switch, and a secondary side control circuit. The secondary side control circuit controls the SR switch to be ON when the power switch is OFF. The secondary side control circuit includes a driving switch for controlling the SR switch, a synchronous control circuit powered by a voltage related to the output voltage, which controls the driving switch to operate the SR switch, and a clamping circuit including a clamping switch and a clamping switch control circuit. The clamping switch control circuit controls the clamping switch according to a current inflow terminal voltage of the clamping switch and/or the voltage related to the output voltage, such that, during a secondary side power-on period, an equivalent impedance of the current inflow terminal of the clamping switch is smaller than a predetermined clamping impedance.

Abstract: A structure of a fly-back power converting apparatus is disclosed. The structure includes a power transistor, a current detector, a pulse width modulation (PWM) signal generator and a current limiter. The power transistor is coupled to an input voltage and receives a PWM signal. The current detector detects a current output from the power transistor and generates a detecting voltage according to the current. The PWM signal generator generates the PWM signal according to a comparing result by comparing the detecting voltage and a standard voltage. The current limiter generates the standard voltage according to a turn-on time of the power transistor.

Abstract: A buck voltage converting apparatus is disclosed. The buck voltage converting apparatus includes a first transistor, a second transistor, an inductor, a controller and a switch. The first transistor receives an input voltage. A first terminal of the inductor is coupled to the first and second transistors. A second terminal of the inductor is coupled to an output terminal of the buck voltage converting apparatus for generating an output voltage. The controller receives the output voltage, and generates a detection voltage according to voltage amplitude of the output voltage. The switch is coupled between a first terminal of the first transistor and a control terminal of the second transistor. The switch is turned on or off according to the detection voltage.

Abstract: A buck voltage converting apparatus is disclosed. The buck voltage converting apparatus includes a first transistor, a second transistor, an inductor, a controller and a switch. The first transistor receives an input voltage. A first terminal of the inductor is coupled to the first and second transistors. A second terminal of the inductor is coupled to an output terminal of the buck voltage converting apparatus for generating an output voltage. The controller receives the output voltage, and generates a detection voltage according to voltage amplitude of the output voltage. The switch is coupled between a first terminal of the first transistor and a control terminal of the second transistor. The switch is turned on or off according to the detection voltage.

Abstract: A buck power converter includes a power transistor, an inductor, a first diode, and an anti-ringing circuit. The power transistor has a first terminal, a second terminal, and a control terminal. The first terminal of the power transistor receives an input voltage, and the control terminal of the power transistor receives a pulse width modulation (PWM) signal. The anti-ringing circuit detects a detection voltage on the second terminal of the power transistor. According to the detection voltage, the anti-ringing circuit provides at least one second diode serially coupled between the second terminal of the power transistor and a reference ground terminal in a forward-biased manner, so as to clamp a voltage swing of the detection voltage.

Abstract: A structure of a fly-back power converting apparatus is disclosed. The structure includes a power transistor, a current detector, a pulse width modulation (PWM) signal generator and a current limiter. The power transistor is coupled to an input voltage and receives a PWM signal. The current detector detects a current output from the power transistor and generates a detecting voltage according to the current. The PWM signal generator generates the PWM signal according to a comparing result by comparing the detecting voltage and a standard voltage. The current limiter generates the standard voltage according to a turn-on time of the power transistor.

Abstract: A power supply protection method for a power supply device includes: detecting whether an output voltage of the power supply device reaches a voltage protection threshold to generate a detection result; generating a first control signal according to a power good input signal and the detection result; utilizing a fault protection circuit to decide whether to output a fault protection signal according to the first control signal; and using a short circuit protection circuit to receive the power good input signal and determining whether to generate a second control signal according to the power good input signal. When the power good input signal is not enabled during a specific time after the power supply device is started, the short circuit protection circuit is directly used to generate the second control signal into the fault protection circuit for triggering the fault protection circuit to output the fault protection signal.