Abstract: An LED dimming method, a dimming controller and system are disclosed. In a phase where a duty cycle of a PWM signal does not exceed a first threshold, every n periods of the PWM signal is taken as one set, taking a set as an output unit, and the duty cycle of the PWM signal is changed by incrementing or decrementing a average duty cycle by a first predetermined amount ?P1 (0<?P1<0.2%), thereby adjusting an output current of an LED. In this way, the duty cycle of the PWM signal can be configured to increment by the first predetermined amount ?P1 that is smaller than 0.2%. Moreover, when the first threshold is 10%, it can be ensured that each period of the PWM signal with duty cycle value within the range of 0-10% can be identified.

Abstract: A control circuit, a control chip and a power supply device are disclosed by the present invention. The control circuits are used for control of a constant-voltage closed-loop which causes a voltage of a voltage feedback signal obtained from an output voltage to approach a voltage of a reference voltage signal obtained from a base voltage and thereby achieves a constant-voltage output. In addition, when a sampled current obtained from an output current is higher than a predetermined current, or when output power is higher than a predetermined power, the control circuit increases the voltage feedback signal or decreases the reference voltage signal, causing the constant-voltage closed loop to decrease the output voltage and the output current and thereby achieving a limited output current and limited output power.

Abstract: A control circuit, system and method for switched-mode power supply are disclosed, the control circuit is for driving a first switch to convert an input voltage into an output voltage. The control circuit includes an on-time control unit, which receives a first signal characterizing switching frequency of first switch and a second signal characterizing current flowing through first switch and responsively generates a signal indicative of a turn-off instant for first switch. When a peak value of the current flowing through the first switch drops below a predefined value, the on-time control unit determines the turn-off instant for the first switch based on the first signal so that the switching frequency of the first switch is maintained at a target frequency. This design can effectively avoid the generation of audible noise, stabilize the output voltage against load changes while maintaining desirable efficiency, and ensure operational safety of the switched-mode power supply.

Abstract: A switched-mode power supply and a control circuit for use in a switched-mode power supply are disclosed. In addition to an EA module, a PWM comparator module and a soft-start voltage generation module, the control circuit also includes an amplitude limiter module for limiting the amplitude of an EA signal based on a soft-start reference voltage and thereby enabling the amplitude of a signal input to the PWM comparator module from the EA module to follow a soft-start control signal and vary stably and smoothly. This can reduce the risk of output voltage and inductor current overshoots due to DC loop establishment during startup of the switched-mode power supply, enhance stability and safety of the power supply system during startup, and accelerate the DC loop establishment.

Abstract: The present invention provides a controller, a switched-mode power supply and a method for controlling a switched-mode power supply. In response to a change of the switched-mode power supply from a continuous conduction mode to a discontinuous conduction mode, slope compensation is carried out with an output peak voltage raised by a compensating DC offset. Moreover, in response to a change of the switched-mode power supply from the discontinuous conduction mode to the continuous conduction mode, the compensating DC offset is subtracted from the peak voltage. In this way, an additional DC offset that would be introduced by a conventional slope compensation approach can be eliminated, maintaining a valley of a sampled feedback voltage constant both under steady load conditions and during load jumps.

Abstract: A control circuit for a switched-mode power converter to generate a control signal for controlling switching transistors in the power converter is disclosed. The control circuit includes: a comparator; a ramp compensation circuit for producing and applying a ramp compensation signal to a first or second input of the comparator; an on-time generation circuit to generate an on-time timer signal; and a control signal generation circuit to generate, based on the comparison signal and the on-time timer signal, the control signal for controlling the switching transistors in the power converter. The ramp compensation signal output from the ramp compensation circuit is configured with: a first slope during an inductor demagnetization interval in operation of the power converter in CCM and a second slope during an inductor demagnetization interval and a zero-current interval in operation of the power converter in DCM, the first slope is greater than the second slope.

Abstract: A control circuit for an isolated power supply is disclosed, the control circuit includes a secondary-side drive signal generator, a secondary-side transistor switch turn-off detector and a primary-side control signal generator. The primary-side control signal generator is configured to: determine a second turn-on instant referring to an turn-off instant of the secondary-side synchronous rectification transistor from the turn-off acknowledgement signal; determine a first turn-on instant referring to a supposed turn-on instant for the primary-side transistor switch from the feedback signal of the output voltage of the isolated power supply; and determine the turn-on instant for the primary-side transistor switch from the second turn-on instant or the first turn-on instant whichever is later, and responsively generate the primary-side transistor switch control signal.

Abstract: A controller chip of a flyback converter, a flyback converter and a switched-mode power supply system are disclosed. In the controller chip, a current scaling module is added, which converts a feedback current signal at a feedback pin of the controller chip to allow compensation capacitor with a small capacitance to be integrated into the chip to constitute a required pole compensation module. In this way, a pole required by the feedback pin FB can be successfully provided in the chip. As a result, filtering of high-frequency noise in a feedback path in which the feedback pin FB is located can be achieved, reducing ripple in an output voltage generated by the flyback converter. Moreover, without changing a sampling gain and the compensation pole, it is allowed to greatly reduce the compensation capacitance, for example, to the order of 10 pF.

Abstract: An output short-circuit protection method, a power management chip and a switched-mode power supply are disclosed. When current accumulation has occurred in a power transistor, the number of consecutive current pulses during which the current accumulation occurred is counted. Upon the number of consecutive current pulses reaches a preset value, a regulation interval spanning switching periods is triggered, for at least some of the switching periods, the leading-edge blanking time is shortened or cancelled. In this way, an excessively large current flowing through the power transistor is prevented. Compared with existing fault response measures for power management chips, restart of the power supply and adjustment of the system timing are not needed, allowing easier implementation. Further, the automatic restart during chip start up due to false triggering as found in the existing measures for power management chips is circumvented.

Abstract: The present invention relates to a multi-phase voltage regulator and a temperature monitoring method thereof. The method includes the following steps of: step 1a: providing a multi-phase voltage regulator including a controller and a plurality of power stages, wherein the controller transmits a corresponding control signal to each of the plurality of power stages, each of the plurality of power stages including a temperature sampling unit, outputs of the temperature sampling units connected to the controller and in parallel with each other; Step 1b: performing time-sharing signal exchange with the temperature sampling unit of the power stages; and Step 1c: when the controller exchanges signals with the temperature sampling unit of a certain power stage, the temperature sampling unit transmits an output signal representing the temperature thereof to the controller via the output.

Abstract: A high power factor control circuit is disclosed, which is used in an AC/DC converter. The converter includes a rectification module, a conversion module and a load. The rectification module receives AC power and rectifies it into a DC current, and the conversion module converts the DC current to drive power as desired by the load and provides it to the load. The conversion module includes a conversion element including an inductive element and a switching element. The control circuit includes a peak limiting signal generator and a switching element control module. The peak limiting signal generator receives a reference signal and produces at least one peak limiting signal from a sample signal. The switching element control module is configured to control switching of the switching element so that, within at least half a line-frequency period, a value of the ripple in the output current flowing through the load is not greater than a limit value.

Abstract: A control circuit for a power converter is disclosed. The power converter includes a switching circuit including a first switching transistor and a second switching transistor. The control circuit includes: a comparator having a first input configured to receive at least a reference signal, a second input configured to receive at least a feedback signal and an output configured to output a comparison signal; a minimum off-time generation circuit; an on-time generation circuit for producing an on-time signal for controlling both the first switching transistor and the second switching transistor; and a ramp compensation circuit configured to generate a ramp compensation signal.

Abstract: A MOSFET device includes an epitaxial region disposed on an upper surface of a substrate, the substrate serving as a drain region in the MOSFET device, and at least two body regions formed in the epitaxial region. The body regions are disposed proximate an upper surface of the epitaxial region and spaced laterally apart. The device further includes at least two source regions disposed in respective body regions, proximate an upper surface of the body regions, and a gate structure including at least two planar gates and a trench gate. Each of the planar gates is disposed on the upper surface of the epitaxial region and overlaps at least a portion of a corresponding body region. The trench gate is formed partially through the epitaxial region and between the body regions.

Abstract: A power supply circuit, a compensation circuit and a harmonic distortion compensation method thereof are disclosed. The power supply circuit includes a rectifier and filter module, a main power stage module, a voltage waveform detection module and a compensation module. The rectifier and filter module converts an AC voltage into a DC voltage. The main power stage module receives the DC voltage and provides power to a load. The voltage waveform detection module is configured to detect a waveform of the DC voltage and derive, from the waveform, information about each cycle of the DC voltage. The compensation module is configured to generate a compensation signal based on the information about each cycle of the DC voltage and trigger the main power stage module to perform compensation operation based on the compensation signal. The compensation operation is performed to accomplish total harmonic distortion compensation of the power supply circuit.

Abstract: A full voltage sampling circuit includes a main sampling circuit, an assist sampling circuit and a processing circuit. The main sampling circuit receives first and second input voltages, and outputs a first sampling signal according to the first and second input voltages. The first sampling signal represents a differential voltage which indicates a difference between the first input voltage and the second input voltage. The assist sampling circuit receives the first and second input voltages, and outputs a second sampling signal according to the first and second input voltages. The second sampling signal represents the differential voltage. The processing circuit is coupled to the main sampling circuit and the assist sampling circuit, and selects a larger one of currents or voltages of the first and second sampling signals as a sampling result to be outputted.

Abstract: Isolated power supply control circuits, isolated power supply and control method thereof are disclosed, the control circuit for controlling an isolated power supply includes a secondary-side control signal generator and a primary-side control signal generator. The secondary-side control signal generator produces a secondary-side transistor switch control signal containing information about a turn-off instant of a secondary-side synchronous rectification transistor, which serves as a second turn-on instant. The primary-side control signal generator derives, from a feedback signal, a supposed turn-on instant for a primary-side transistor switch, which serves as a first turn-on instant. The primary side turn-on signal generator further derives a turn-on instant for the primary-side transistor switch from the second or first turn-on instant whichever is later and responsively generates a primary-side transistor switch control signal.

Abstract: A switch-mode power supply (SMPS), an SMPS system and a power supply method for an SMPS system are disclosed. The SMPS controller includes an output-voltage power supply unit, a built-in energy storage unit and a logic control unit. The output-voltage power supply unit is configured to charge the built-in energy storage unit using an output voltage from the SMPS system so that the built-in energy storage unit can provide an operating voltage for the logic control unit. The use of a stand-off energy storage capacitor can be dispensed with, and the use of the output voltage as a power supply is enabled. As a result, significant reductions in overall and standby power dissipation are achieved. In addition, the SMPS controller may further include a high-voltage power supply unit, which provides a hybrid power supply solution, together with the output-voltage power supply unit.

Abstract: A control circuit for a constant-current drive circuit, as well as a constant-current drive circuit are disclosed. The control circuit can obtain output information of the constant-current drive circuit and use it in combination with reference information to determine, according to an output condition corresponding to the current load of the constant-current drive circuit, a time point for the system to enter or exit a rapid drive mode. Therefore, it can be suitably used in various application scenarios to determine a time point for the system to entry into or exit from the rapid start mode. Compared with fast charging for a fixed period of time as used in the prior art, embodiments of the present invention can effectively overcome the problem of easy overshooting or inadequate acceleration during start as found in various applications.

Abstract: An LDMOS device includes a semiconductor substrate of a first conductivity type, a doped drift region of a second conductivity type formed on at least a portion of the substrate, and a body region of the first conductivity type formed in the drift region. Source and drain regions of the second conductivity type are formed proximate an upper surface of the body region and drift region, respectively, and spaced laterally from one another. A gate structure is disposed between the source and drain regions and includes a control gate formed over the body region, and a field plate formed over the drift region, the gate structure being electrically isolated from the body and drift regions by a first insulating layer. An oxide structure is formed on a portion of the field plate and a portion of the drift region, the oxide structure overlapping a corner of the field plate.

Abstract: A control circuit, system and method for switched-mode power supply are disclosed, the control circuit is for driving a first switch to convert an input voltage into an output voltage. The control circuit includes an on-time control unit, which receives a first signal characterizing switching frequency of first switch and a second signal characterizing current flowing through first switch and responsively generates a signal indicative of a turn-off instant for first switch. When a peak value of the current flowing through the first switch drops below a predefined value, the on-time control unit determines the turn-off instant for the first switch based on the first signal so that the switching frequency of the first switch is maintained at a target frequency. This design can effectively avoid the generation of audible noise, stabilize the output voltage against loading changes while maintaining desirable efficiency, and ensure operational safety of the switched-mode power supply.