A flyback converter having an active snubber includes a transformer to receive input power. The transformer has a primary winding at a first side. The active snubber is coupled in parallel with two ends of the primary winding and has a first circumferential circuit coupling in parallel with the primary winding, a second circumferential circuit and a zero voltage switch unit. The second circumferential circuit is controlled by the zero voltage switch unit and incorporated with the first circumferential circuit to form double damping paths to reduce current and prevent resonance that might otherwise occur to a single circumferential circuit and the secondary side of the transformer.
The present invention discloses a protection architecture for a multi-lamp system, which applies to a multi-lamp driving system for driving a plurality of lamp loops. The present invention is characterized in that two opposite-phase loads of a loop are separately defined to be a first load and a second load, and that a voltage-division/detection loop is formed via cascading a first voltage-division element to a second voltage-division element and is coupled to between the first load and the second load to detect an abnormal current, wherein the second voltage-division element is coupled to a ground terminal, and wherein a signal-acquiring terminal is coupled to between the first voltage-division element and the second voltage-division element and acquires an abnormal voltage signal for a protection unit from the abnormal current, and wherein the protection unit detects the abnormal voltage signal and shuts off the driving system.
The present invention is related to an improved transformer structure including a main body and, accommodated in the main body, a first winding frame and two winding frames. Hollow portions of the first winding frame and each of the second winding frames are combined with openings on the main body, for forming a primary side passage in a longitudinal direction and two secondary side passages in a lateral direction, so as to penetrate respectively a first magnetic material into the primary side passage and a second magnetic material into the two secondary side passages. Through the longitudinal primary side passage and the lateral secondary side passages, the primary and the secondary side winding can have a proper interval therebetween for achieving a stable output, so that a high voltage can be directly applied to the transformer for driving the large size LCD back light module for improving the efficiency.
The present invention discloses a variable-frequency circuit with a compensation mechanism, which comprises: a load sensing/decision unit, a frequency-division unit and a level modulation unit. The present invention applies to a power supply having a frequency-division mode. The power supply has a feedback unit generating a feedback signal. The load sensing/decision unit determines the operational mode according to the feedback signal. The frequency-division unit generates a reference frequency signal. The level modulation unit generates a reference level signal. During frequency variation, the level modulation unit generates a compensation current to modulate the reference level signal. Thereby, the PWM unit of the power supply can adjust the working cycle of the power supply according to the reference frequency signal, the reference level signal and the feedback signal.
The present invention discloses a method and a circuit for controlling a start-up cycle of an integrated circuit in a circuit system. The method and circuit determine whether or not an input power of the circuit system and a bias voltage power of the integrated circuit have reached a normal operating voltage range to control the bias voltage power to produce a start-up cycle of the integrated circuit. The method and circuit also provides a protection mechanism for an overload of the circuit system overload, so that the integrated circuit can moderate surges and prevent damages.