Abstract: A bleeder current control method. The bleeder current control method includes the following steps: The rectifier bridge transmits a post-bridge input signal to the power system. The shaping circuit obtains the post-bridge input signal and shapes it into a bleeder current reference signal, the bleeder current reference signal is inversely correlated with the initial post-bridge input signal. Acquiring a current sampling signal representing the bleeder current, and comparing the error of the current sampling signal with the bleeder current reference signal to obtain an error signal. The current sampling signal is controlled according to the error signal, so that the current sampling signal is output based on the waveform of the bleeder current reference signal. Thus, a reliable and full-time sine wave envelope signal is provided to the power system, so as to reduce the loss caused by the bleeder current to the power system.

Abstract: A bleeder current control method. The bleeder current control method includes the following steps: The rectifier bridge transmits a post-bridge input signal to the power system. The shaping circuit obtains the post-bridge input signal and shapes it into a bleeder current reference signal, the bleeder current reference signal is inversely correlated with the initial post-bridge input signal. Acquiring a current sampling signal representing the bleeder current, and comparing the error of the current sampling signal with the bleeder current reference signal to obtain an error signal. The current sampling signal is controlled according to the error signal, so that the current sampling signal is output based on the waveform of the bleeder current reference signal. Thus, a reliable and full-time sine wave envelope signal is provided to the power system, so as to reduce the loss caused by the bleeder current to the power system.

Abstract: A non-isolating AC-DC voltage converting system has two voltage converters. The first voltage converter receives a bus voltage and turns on a power transistor when the bus voltage is at valley regions and to provide an interim voltage which is lower than the bus voltage. The second voltage converter receives the interim voltage and provides an output voltage of the AC-DC voltage converting system.

Abstract: A control circuit for controlling a power switch in a SMPS has a signal jittering circuit and a comparing circuit. The signal jittering circuit adds an overlapping signal into a current sensing signal indicative of current flowing through the power switch or into a current threshold signal, wherein the overlapping signal has a first frequency and an enveloping line of the overlapping signal has a second frequency, and wherein the second frequency is lower than the first frequency. The comparing circuit compares the current sensing signal and the current threshold signal, wherein when the current sensing signal is higher than the current threshold signal, the control circuit c turns off the power switch.

Abstract: A control circuit for controlling a power switch in a SMPS has a signal jittering circuit and a comparing circuit. The signal jittering circuit adds an overlapping signal into a current sensing signal indicative of current flowing through the power switch or into a current threshold signal, wherein the overlapping signal has a first frequency and an enveloping line of the overlapping signal has a second frequency, and wherein the second frequency is lower than the first frequency. The comparing circuit compares the current sensing signal and the current threshold signal, wherein when the current sensing signal is higher than the current threshold signal, the control circuit c turns off the power switch.

Abstract: A non-isolating AC-DC voltage converting system has two voltage converters. The first voltage converter receives a bus voltage and turns on a power transistor when the bus voltage is at valley regions and to provide an interim voltage which is lower than the bus voltage. The second voltage converter receives the interim voltage and provides an output voltage of the AC-DC voltage converting system.