Abstract: An AC-to-DC power converting apparatus includes a power factor correction circuit generating a DC output voltage based on a rectified voltage obtained through rectifying an AC input voltage and on a PWM signal generated based on an adjustment current and a predetermined ramp signal. A multiplier-divider circuit includes: a ramp generating unit generating a ramp signal based on a clock signal and on a first detection voltage associated with the rectified voltage; a control unit generating a control signal based on the clock signal, the ramp signal, and a detection voltage generated based on the DC output voltage; and an output unit generating an adjustment signal based on an input signal associated with the rectified voltage and the control signal.

Abstract: A light emitting system includes a series connection of a light emitting unit and a variable current source, and a voltage conversion device that includes a rectifier circuit and an output circuit. The rectifier circuit rectifies an AC voltage to generate a rectified voltage across a first rectifier output coupled to one end of the series connection of the light emitting unit and the variable current source, and a second rectifier output. The output circuit is coupled between the second rectifier output and another end of the series connection of the light emitting unit and the variable current source, and is configured to generate a direct-current (DC) output voltage.

Abstract: A level shifter includes an input stage circuit, a latch circuit and a transient speed-up circuit. The input stage circuit receives an input signal. The latch circuit is coupled to the input stage circuit through a first output terminal and a second output terminal, and determining steady-state levels of the first and the second output terminals according to the input signal. The transient speed-up circuit is coupled to the first and the second output terminals. When the transient speed-up circuit determines the first and the second output terminals are at the same logic level, the transient speed-up circuit accelerates the positive edge transition of the first or the second terminals.

Abstract: Serially connected low voltage transistors are used to replace a high voltage transistor in a voltage conversion circuit for a driver, or parallel connected sub-transistors are used to establish a high voltage transistor having an effective size dynamically adjusted according to loading of the driver, to reduce switching loss and thereby improve the efficiency of the driver.

Abstract: A level shifter includes an input stage circuit, a latch circuit and a transient speed-up circuit. The input stage circuit receives an input signal. The latch circuit is coupled to the input stage circuit through a first output terminal and a second output terminal, and determining steady-state levels of the first and the second output terminals according to the input signal. The transient speed-up circuit is coupled to the first and the second output terminals. When the transient speed-up circuit determines the first and the second output terminals are at the same logic level, the transient speed-up circuit accelerates the positive edge transition of the first or the second terminals.

Abstract: A switching power converting apparatus includes a voltage conversion module, a detecting unit, and a switching signal generating unit. The voltage conversion module converts an input voltage into an output voltage associated with a secondary side current, which flows through a secondary winding of a transformer and is generated based on a switching signal. The detecting unit generates a detecting signal based on the output voltage and a predetermined reference voltage. The switching signal generating unit generates the switching signal based on the detecting signal and an adjusting signal so that the secondary side current is gradually increased during a start period of the switching power converting apparatus.

Abstract: A voltage converter controller and a voltage converter circuit, either of which includes a voltage-drop compensating circuit for compensating a voltage drop between an output voltage and a load. The voltage-drop compensating circuit includes a trans-conductance stage and a squarer. The trans-conductance stage outputs a compensating sink current to a voltage dividing terminal of the output voltage and outputs a compensating source current to a reference voltage terminal of an error amplifier. An input terminal of the squarer is coupled to an output terminal of the error amplifier. An output terminal of the squarer is coupled to an input terminal of the trans-conductance stage.

Abstract: A phase/frequency detector module, applicable to a digital phase-locked loop, includes: an edge detector for receiving a reference clock signal and a counting clock signal, where when a positive edge of the counting clock signal occurs, if a positive edge of the reference clock signal has occurred, the edge detector outputs an edge-detected signal, else the edge detector outputs an edge-not-detected signal; a counter coupled to the edge detector, where if receiving the edge-detected signal, the counter outputs a counting result forming a frequency error signal, resets, and loads a count value, and if receiving the edge-not-detected signal, the counter continues to count on the positive edge of the counting clock signal; and a frequency phase converter for performing integration over the counting result, where the integral forms a phase error signal.

Abstract: A control circuit and method for a PWM voltage regulator combine a high frequency feedback technique with a constant on-time or constant off-time topology to improve the transient performance of the PWM voltage regulator. The PWM voltage regulator generates a constant on-time or constant off-time depending on a current for generating a PWM signal, and dynamically adjusts the current according to the droop-voltage at its output during a transient period. Therefore, the PWM voltage regulator boosts its transient response without any threshold for load step detection.

Abstract: A method and apparatus for dynamically adjusting a dead time of a BLDC motor during a phase change detect the winding current of the BLDC motor during the dead time, and terminate the dead time when the winding current is detected to be substantially or close to zero. Thus, the method and apparatus can optimize the dead time and switch the BLDC motor between two phases at a zero-current point, without reducing the maximum rotation speed of the BLDC motor.

Abstract: An LED driving device includes: a rectifying circuit for outputting a DC voltage to a string of M LED units; (M?1) first switching circuits each coupled between a corresponding one of first to (M?1)th LED units and ground; and a second switching circuit coupled between an Mth LED unit and ground. When the DC voltage is sufficient to turn on first to kth LED units, where 1?k?M, the kth LED unit is coupled to ground through first and second conductive paths provided by a resistor unit, and a corresponding first switching circuit or the second switching circuit, and each of the first to (k?1)th LED units is coupled to ground through a third conductive path provided by a corresponding first switching circuit and the resistor unit.

Abstract: An LED driving device includes: a rectifying circuit for outputting a DC voltage to a string of M LED units; (M?1) first switching circuits each coupled between a corresponding one of first to (M?1)th LED units and ground; and a second switching circuit coupled between an Mth LED unit and ground. When the DC voltage is sufficient to turn on first to kth LED units, where 1?k?M, the kth LED unit is coupled to ground through first and second conductive paths provided by a resistor unit, and a corresponding first switching circuit or the second switching circuit, and each of the first to (k?1)th LED units is coupled to ground through a third conductive path provided by a corresponding first switching circuit and the resistor unit.

Abstract: A parameter setting circuit and method for an integrated circuit apply a pulse current to a pin of the integrated circuit during a programming mode of the integrated circuit, and then extract the difference between the voltage on the pin and the DC component of the voltage on the pin to determine a setting signal for parameter setting to an internal circuit of the integrated circuit. By this way, an input pin, an output pin or an input/output pin of the integrated circuit may be used as the pin implementing the parameter setting function.

Abstract: A power converter includes a rectifier and a power factor corrector. The rectifier is to be coupled to an alternating current power source and is configured to output a rectified signal. The power factor corrector includes a correcting circuit and a control circuit. The correcting circuit receives the rectified signal and is configured to generate an output voltage based on the rectified signal and a driving signal. The control circuit is configured to generate a first to-be-compared signal based on the rectified signal, to generate a second to-be-compared signal based on the output voltage, to compare the first and second to-be-compared signals, and to generate the driving signal based on a result of comparison performed thereby.

Abstract: A wireless power receiver includes a power receiving circuit wirelessly receiving power transmitted from a wireless power transmitter so as to generate an induced current, and a rectifying-and-modulating circuit including first to eighth switches and a control unit. The control unit is operable to control operation of each of the first to eighth switches between conduction and non-conduction. Accordingly, the first to fourth switches cooperatively constitute a full-bridge rectifier for rectifying the induced current generated by the power receiving circuit, and each of the fifth to eighth switches is operable to switch synchronously with a respective one of the first to fourth switches or to became non-conducting, thereby changing an amplitude of the induced current.

Abstract: A flyback converter includes a transformer to convert an input voltage into an output voltage, a control circuit senses a primary current of the transformer to generate a current sense signal, and a sensing circuit is configured to sense a variation of the current sense signal between two time points for extracting the input voltage information therefrom.

Abstract: A hysteretic mode LED driver for providing a driving current for an LED includes a hysteretic comparing circuit and a feedback loop. The hysteretic comparing circuit compares a driving current related sensing signal with a reference signal to control the average value of the driving current. The feedback loop senses the error between the average value of the driving current and a target value to adjust the reference signal or the offset of the hysteretic comparing circuit to adjust the average value of the driving current.

Abstract: An oscillator circuit includes: a switched-capacitor filter filtering a voltage at a common node between a current generating unit and a frequency-controlled resistor so as to generate a filtered voltage; an amplifier generating a control voltage based on the filtered voltage and a voltage at a common node between the current generating unit and a reference resistor; a voltage-controlled oscillator generating an oscillation signal based on the control voltage; and a control signal generating unit generating, based on the oscillation signal, a control input having a frequency proportional to that of the oscillation signal. The frequency-controlled resistor has a resistance variable according to the control input.

Abstract: A light emitting diode driver includes: a serial-to-parallel conversion unit converting, based on a reference clock signal, a serial input signal carrying a number (N) of M-bit gray codes into a parallel input signal carrying the M-bit gray codes; a counting unit counting an output control signal to output a counting value; a data buffer unit storing, based on a latch signal, the M-bit gray codes carried by the parallel input signal, and outputting, based on the counting value and the M-bit gray codes, an N-bit signal consisting of N bits, each of which is an ith one of M bits of a respective M-bit gray code, where i is associated with the counting value; and an output unit generating a number (N) of driving current signals based on at least the N-bit signal.

Abstract: A power supply uses a power converter to generate a regulated voltage by referencing to a first DC voltage, a low dropout (LDO) regulator to generate an output voltage from the regulated voltage by referencing to a second DC voltage, and a reference voltage generator to dynamically adjust the first DC voltage according to the input voltage and the control voltage of the output transistor of the LDO regulator. The dropout voltage of the LDO regulator can be minimized to maintain the high efficiency of the power supply at different loading or selected output voltages.