Abstract:
A switch control circuit for controlling a first switch element and a second switch element within a bridgeless switching circuit is provided. The bridgeless switching circuit generates an output signal according to an alternating current signal. The switch control circuit includes a current generating element and a phase generating element. The current generating element is for sensing a first current flowing through the first switch element and a second current flowing through the second switch element, and generating a phase comparison result according to the first and the second currents. The phase generating element generates a first control signal and a second control signal according to a power factor correction signal and the phase comparison result to control conducting status of the first and the second switch elements, respectively.
Abstract:
A passive current balance driving apparatus has a circuit topology composed by several simple passive components and is capable of driving a plurality of LED strings simultaneously. The present passive current balance driving apparatus is mainly configured such that each LED string has the identical load characteristics during the positive and negative half cycles of the AC power. As such, the currents flowing through the respective LED strings are basically/substantially equal, thereby achieving the current balance.
Abstract:
A snubber circuit includes: at least one impedance component, a capacitor, and a Bipolar Junction Transistor (BJT). The snubber circuit is utilized for protecting electric/electronic components, reducing high frequency interference and spike voltage, and enhancing efficiency. In particular, the at least one impedance component in the snubber circuit can be at least one zener diode, where regarding protecting electric/electronic components, reducing high frequency interference and spike voltage, and enhancing efficiency, the performance of the snubber circuit in a situation where the zener diode is utilized is better than that of the snubber circuit in a situation where other types of impedance components are utilized. An associated method of using a BJT in a snubber circuit is also provided.
Abstract:
A switching power supply apparatus including an AC-to-DC conversion circuit, a hysteretic relay and a relay control circuit is provided. The AC-to-DC conversion circuit includes a current limit resistor, and the current limit resistor is configured to suppress an inrush current generated during the AC-to-DC conversion circuit converts an AC input voltage into a DC output voltage. The hysteretic relay is coupled with the current limit resistor in parallel. The relay control circuit is coupled to the AC-to-DC conversion circuit and the hysteretic relay, and configured to control the hysteretic relay to turn on in response to one of an over drive pulse signal and a holding modulation signal when the DC output voltage reaches to a predetermined value, so as to bypass the current limit resistor, wherein an enabling time of the over drive pulse signal is different from that of the holding modulation signal.
Abstract:
A grounding method adapted for a power supply (for example, an adapter power supply, a three-phase AC-to-DC power supply, a DC-to-DC power supply, . . . , etc., but not limited thereto) is provided, and which includes: (a) providing a circuit body corresponding to the power supply, where the circuit body has an input part and an output part; (b) disposing the circuit body in a shielding layer; and (c) making at least one of the input part and the output part to be coupled with the shielding layer through at least one capacitor. In this case, the present invention can effectively solve the problem of common-mode interferences in the power supply.
Abstract:
A non-isolated resonant converter is provided. The provided non-isolated resonant converter includes a switch circuit, a resonant circuit and a rectifying-filtering circuit. The switch circuit, the resonant circuit and the rectifying-filtering circuit are sequentially connected. The resonant circuit includes an auto-transformer, a capacitor and an inductor, wherein the capacitor and the inductor are connected to the auto-transformer. The configuration of the provided non-isolated resonant converter has small size, low loss and high power density.
Abstract:
A method of controlling fan speed is provided. The method includes: setting a target speed of the fan; providing an actual control speed signal and using the actual control speed signal to drive the fan so as to obtain an actual speed of the fan; determining whether the actual speed of the fan is equal to the set target speed; and when the actual speed of the fan is equal to the set target speed, continuously using the provided actual control speed signal to drive the fan, otherwise, gradually compensating the intensity of the provided actual control speed signal until the actual speed of the fan is equal to the set target speed after the fan is driven by the gradually compensated actual control speed signal.
Abstract:
A power factor correction (PFC) circuit includes an inductor, a diode, a storage capacitor, a switch and a control unit. The input power has a voltage fluctuation V1. The storage component absorbs a first voltage fluctuation and a switch regulation circuit absorbs a second voltage fluctuation V2. Thus output voltage from the PFC circuit is not a conventional constant voltage but a voltage of a great ripple. The PFC circuit further has a harmonic regulation unit. The harmonic regulation unit generates a voltage signal containing 3rd harmonic. The control unit receives a feedback signal and the voltage signal containing 3rd harmonic to generate a reference to the inductor current. Therefore, the inductor current contains 3rd harmonic. Thus power fluctuation absorbed and released by the capacitor is smaller. As a result energy storage capacitance can be reduced significantly.
Abstract:
A power supply apparatus is provided. The power supply apparatus includes two power suppliers coupled in parallel so as to simultaneously supply the electric power required by an electronic product in operation. The power supply apparatus provided by the invention may stably/accurately output the desired DC output voltage to the electronic product, and may further in advance increase a main power generated inside the other power supplier when one of the power suppliers is over voltage, thereby avoiding an oversized voltage drop from occurring in the DC output voltage.
Abstract:
A power transforming circuit board includes a substrate and at least one power output structure. The substrate has at least one power transforming circuit and at least one pair of power input holes. The power output structure is disposed on the substrate. Each power output structure is electrically connected with one corresponding power transforming circuit. Each power output structure has at least one cable connecting hole. The normal direction of each power output structure is oriented at an angle with respect to the normal direction of the substrate.