Abstract: A switching mode power supply (SMPS) includes a transformer having a primary winding for coupling to an input power source, a secondary winding for providing an output voltage of the SMPS, and an auxiliary winding. The SMPS also has a power transistor coupled to the primary winding and a primary side control circuit coupled to the auxiliary winding and the power transistor. The primary side control circuit is configured to regulate the output of the SMPS by controlling the power switch in response to a feedback voltage signal that is representative of an output of the SMPS. The SMPs also has a secondary-side control circuit coupled to the secondary winding and being configured to cause the output voltage of the SMPS to discharge when the output voltage of the SMPS is higher than a first reference voltage.

Abstract: A switching mode power supply (SMPS) includes a transformer having a primary winding for coupling to an input power source, a secondary winding for providing an output voltage of the SMPS, and an auxiliary winding. The SMPS also has a power transistor coupled to the primary winding and a primary side control circuit coupled to the auxiliary winding and the power transistor. The primary side control circuit is configured to regulate the output of the SMPS by controlling the power switch in response to a feedback voltage signal that is representative of an output of the SMPS. The SMPs also has a secondary-side control circuit coupled to the secondary winding and being configured to cause the output voltage of the SMPS to discharge when the output voltage of the SMPS is higher than a first reference voltage.

Abstract: A switched mode power supply (SMPS) includes a transformer with a primary winding, a secondary winding, an auxiliary winding, and a power switch coupled to the primary winding. During one switching cycle, the auxiliary winding provides a feedback signal which includes a first voltage pulse that is induced after the power switch is turned on and a second voltage pulse that is induced after the power switch is turned off. A control circuit includes a circuit for generating a sampling signal for sampling the second voltage pulse in a switching cycle at a time that is determined based on the first voltage pulse in the same switching cycle. A sample-and-hold circuit is configured for sampling and storing the second voltage pulse in response to the sampling signal. A switching signal generating circuit is configured to generate a switching signal for controlling the power switch based on an output of the sample-and-hold circuit.

Abstract: A control circuit is configured for controlling a power switch to regulate an output of a power converter. The control circuit is configured to increase a switching frequency of the power switch when a first signal representing a magnitude of the power converter is below a first output level. In some embodiment, the first output level is selected such that when the first signal is below the first output level, the power converter may generate audible noise. In an embodiment, when the first signal is above the first output level, the control circuit is configured to turn off the power switch when a second signal representing a current in the power switch is above a first reference level. On the other hand, when the first signal is below the first output level, the control circuit is configured to turn off the power switch if the second signal reaches a lower reference level.

Abstract: A switching mode power supply (SMPS) includes a transformer having a primary winding for coupling to an input power source, a secondary winding for providing an output voltage of the SMPS, and an auxiliary winding. The SMPS also has a power transistor coupled to the primary winding and a primary side control circuit coupled to the auxiliary winding and the power transistor. The primary side control circuit is configured to regulate the output of the SMPS by controlling the power switch in response to a feedback voltage signal that is representative of an output of the SMPS. The SMPs also has a secondary-side control circuit coupled to the secondary winding and being configured to cause the output voltage of the SMPS to discharge when the output voltage of the SMPS is higher than a first reference voltage.

Abstract: A control circuit is configured for controlling a power switch to regulate an output of a power converter. The control circuit is configured to increase a switching frequency of the power switch when a first signal representing a magnitude of the power converter is below a first output level. In some embodiment, the first output level is selected such that when the first signal is below the first output level, the power converter may generate audible noise. In an embodiment, when the first signal is above the first output level, the control circuit is configured to turn off the power switch when a second signal representing a current in the power switch is above a first reference level. On the other hand, when the first signal is below the first output level, the control circuit is configured to turn off the power switch if the second signal reaches a lower reference level.

Abstract: A switched mode power supply (SMPS) includes a transformer with a primary winding, a secondary winding, an auxiliary winding, and a power switch coupled to the primary winding. During one switching cycle, the auxiliary winding provides a feedback signal which includes a first voltage pulse that is induced after the power switch is turned on and a second voltage pulse that is induced after the power switch is turned off. A control circuit includes a circuit for generating a sampling signal for sampling the second voltage pulse in a switching cycle at a time that is determined based on the first voltage pulse in the same switching cycle. A sample-and-hold circuit is configured for sampling and storing the second voltage pulse in response to the sampling signal. A switching signal generating circuit is configured to generate a switching signal for controlling the power switch based on an output of the sample-and-hold circuit.