Abstract: A transmission interface with noise reduction function includes a first circuit and a second circuit, for transmitting a signal from the first circuit to the second circuit or from the second circuit to the first circuit. The first circuit includes a first sub-winding and a first wire unit, and the second circuit includes a second sub-winding and a second wire unit. When an electromagnetic noise passes through the first sub-winding and the first wire unit, two loop currents are respectively generated, and the currents have opposite directions to cancel each other so as to reduce the electromagnetic noise. Or, when an emitting current corresponding to the signal flows through the first sub-winding and the first wire unit, two magnetic fields are respectively generated, and the magnetic fields have opposite directions to cancel each other so as to reduce the electromagnetic interference.

Abstract: A light emitting device circuit has one or plural light emitting devices connected in series. A light emitting device driver circuit drives the light emitting device circuit according to a rectified input voltage. The light emitting device driver circuit includes a power switch and a control circuit. When the power switch is conductive, a light emitting device current flows through the light emitting device circuit and the power switch. When the power switch is not conductive, an output capacitor discharges to provide the light emitting device current. The control circuit determines whether the rectified input voltage is lower or not lower than a forward voltage plus a reference voltage according to a voltage at a reverse end of the light emitting device circuit, and control the power switch accordingly.

Abstract: A linear LED driver comprises a transistor having an input terminal coupled to a LED. When the transistor is turned on, the LED is lighted. The linear LED driver further includes a protection circuit for judging whether an instant high voltage variation occurs or not according to at least one of the voltages of a control terminal and an output terminal of the transistor so as to achieve a protection function.

Abstract: A soft-start switching power converter includes a voltage converting circuit and a soft-start circuit. The voltage converting circuit includes a transformer, and a first switch which includes a first terminal connected to the transformer, a second terminal providing a trigger signal, and a control terminal receiving a control signal, and which is controlled to switch between conduction and nonconduction, such that the transformer generates a feedback voltage. The soft-start circuit receives the trigger signal, generates the control signal according to the trigger signal, and determines whether or not to clamp the control signal at a preset voltage level based on the trigger signal.

Abstract: A driver circuit of a LED luminance device includes: a signal pin; a determining circuit for determining the magnitude of an input signal; an indication signal generating circuit for outputting an indication signal to the signal pin according to the determining result of the determining circuit; an alignment signal generating circuit for generating an alignment signal when triggered by a predetermined edge of a signal at the signal pin; an indication signal detecting circuit for detecting the signal at the signal pin to generate a detection signal; and a control signal generating circuit for generating multiple control signals according to the detection signal to respectively control multiple switching elements in parallel connection with multiple LED devices when triggered by the alignment signal.

Abstract: A linear LED driver includes a voltage supply terminal providing a driving voltage, at least one first transistor, each of which has an input terminal coupled to a respective LED, and a bleeder circuit. When the voltage of the output terminal of each of the at least one first transistor is lower than a first threshold and a power voltage is higher than a second threshold, the bleeder circuit will generate a bleeder current to discharge the voltage supply terminal so as to prevent the LEDs from flickering. The bleeder circuit detects the voltage of the output terminal of each of the at least one first transistor. Therefore, whether the LEDs are lighted up can be confirmed so that the bleeder current can be provided at properly time point.

Abstract: A linear LED driver includes a voltage supply terminal providing a driving voltage, at least one first transistor, each of which has an input terminal coupled to a respective LED, and a bleeder circuit. When the voltage of the output terminal of each of the at least one first transistor is lower than a first threshold and a power voltage is higher than a second threshold, the bleeder circuit will generate a bleeder current to discharge the voltage supply terminal so as to prevent the LEDs from flickering. The bleeder circuit detects the voltage of the output terminal of each of the at least one first transistor. Therefore, whether the LEDs are lighted up can be confirmed so that the bleeder current can be provided at properly time point.

Abstract: A linear LED driver comprises a transistor having an input terminal coupled to a LED. When the transistor is turned on, the LED is lighted. The linear LED driver further includes a protection circuit for judging whether an instant high voltage variation occurs or not according to at least one of the voltages of a control terminal and an output terminal of the transistor so as to achieve a protection function.

Abstract: The present invention discloses a light emitting device driver chip for driving light emitting devices in series. The chip includes: plural pins electrically connected to corresponding light emitting devices, respectively, wherein an internal voltage is provided through a predetermined one of the pins; a voltage regulation circuit for providing an operation voltage according to the internal voltage; a switch circuit including plural switch groups electrically connected to corresponding pins, respectively; a current source circuit for providing a current to the light emitting devices; and a switch control circuit for controlling the switch groups to determine which light emitting device is turned ON. The light emitting device driver chip does not directly receive the rectified input voltage.

Abstract: The present invention discloses a light emitting device driver chip for driving light emitting devices in series. The chip includes: plural pins electrically connected to corresponding light emitting devices, respectively, wherein an internal voltage is provided through a predetermined one of the pins; a voltage regulation circuit for providing an operation voltage according to the internal voltage; a switch circuit including plural switch groups electrically connected to corresponding pins, respectively; a current source circuit for providing a current to the light emitting devices; and a switch control circuit for controlling the switch groups to determine which light emitting device is turned ON. The light emitting device driver chip does not directly receive the rectified input voltage.

Abstract: The present invention discloses a light emitting device driver circuit and a driving method of a light emitting device circuit. The light emitting device driver circuit is for driving a light emitting device circuit with plural light emitting devices connected in series. The light emitting device driver circuit determines a number of the conductive light emitting devices according to a rectified input voltage. The light emitting device driver circuit includes: a switch module, a current source circuit, and a total harmonic distortion (THD) compensation circuit. The THD compensation circuit generates an adjustment current according to the rectified input voltage. The current source circuit provides a light emitting device current to the light emitting device circuit according to the adjustment current, such that the THD is reduced.

Abstract: The present invention discloses a light emitting device driver circuit. The light emitting device driver circuit drives a light emitting device circuit. The light emitting device circuit includes plural light emitting devices connected in series and a diode circuit, wherein the plural light emitting devices are divided to plural groups. The light emitting device driver circuit includes: a first switch circuit, a second switch circuit, a current source circuit, and a control circuit. The first switch circuit includes plural first switches connected in parallel to the corresponding groups respectively. The second switch circuit includes plural second switches coupled to a forward end and a reverse end of the diode circuit respectively, wherein the second switch circuit determines whether to conduct the forward end or the reverse end to the current source circuit according to the voltages of the forward end and the reverse end.

Abstract: The present invention discloses a light emitting device driver circuit. The light emitting device driver circuit drives a light emitting device circuit. The light emitting device circuit includes plural light emitting devices connected in series and a diode circuit, wherein the plural light emitting devices are divided to plural groups. The light emitting device driver circuit includes: a first switch circuit, a second switch circuit, a current source circuit, and a control circuit. The first switch circuit includes plural first switches connected in parallel to the corresponding groups respectively. The second switch circuit includes plural second switches coupled to a forward end and a reverse end of the diode circuit respectively, wherein the second switch circuit determines whether to conduct the forward end or the reverse end to the current source circuit according to the voltages of the forward end and the reverse end.

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: The present invention discloses a light emitting device driver circuit and a driving method of a light emitting device circuit. The light emitting device driver circuit is for driving a light emitting device circuit with plural light emitting devices connected in series. The light emitting device driver circuit determines a number of the conductive light emitting devices according to a rectified input voltage. The light emitting device driver circuit includes: a switch module, a current source circuit, and a total harmonic distortion (THD) compensation circuit. The THD compensation circuit generates an adjustment current according to the rectified input voltage. The current source circuit provides a light emitting device current to the light emitting device circuit according to the adjustment current, such that the THD is reduced.

Abstract: A retaining circuit includes: a low dropout regulator (LDO) circuit for generating a primary operation voltage, a secondary operation voltage generation (SOVG) circuit, and a memory circuit. The SOVG circuit generates a secondary operation voltage, and the memory circuit is powered by the secondary operation voltage to store at least one operation parameter, such that when the primary operation voltage is lower than a non-controlled level, the memory circuit holds the operation parameter to sustain operation.

Abstract: The present invention provides a light emitting device power supply circuit with dimming function and a control circuit thereof. The light emitting device power supply circuit includes: a phase-cut dimming circuit, a rectifier circuit, a transformer circuit, and a control circuit. The transformer circuit includes an auxiliary winding, which is coupled to a primary winding, for generating a bleeder current to keep a conduction current higher than a holding current and prevent the phase-cut dimming circuit from turning OFF when the phase-cut dimming circuit operates in conductive phase. The control circuit includes a waveform analysis circuit, a bleeder current control circuit, and a bleeder current source. The bleeder current source includes a linear regulator or a variable current source. The bleeder current source controls the bleeder current so that the bleeder current is generated in a continuous and non-switching manner within the conductive phase.

Abstract: The present invention provides a light emitting device power supply circuit with dimming function and a control circuit thereof. The light emitting device power supply circuit includes: a phase-cut dimming circuit, a rectifier circuit, a transformer circuit, and a control circuit. The transformer circuit includes an auxiliary winding, which is coupled to a primary winding, for generating a bleeder current to keep a conduction current higher than a holding current and prevent the phase-cut dimming circuit from turning OFF when the phase-cut dimming circuit operates in conductive phase. The control circuit includes a waveform analysis circuit, a bleeder current control circuit, and a bleeder current source. The bleeder current source includes a linear regulator or a variable current source. The bleeder current source controls the bleeder current so that the bleeder current is generated in a continuous and non-switching manner within the conductive phase.

Abstract: A soft-start switching power converter includes a voltage converting circuit and a soft-start circuit. The voltage converting circuit includes a transformer, and a first switch which includes a first terminal connected to the transformer, a second terminal providing a trigger signal, and a control terminal receiving a control signal, and which is controlled to switch between conduction and nonconduction, such that the transformer generates a feedback voltage. The soft-start circuit receives the trigger signal, generates the control signal according to the trigger signal, and determines whether or not to clamp the control signal at a preset voltage level based on the trigger 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.