A current matching circuit includes a plurality of LED driver circuits. A current to voltage converter circuit is coupled to the plurality of LED driver circuits to generate a plurality of voltage signals. Each one of the plurality of voltage signals is representative of a respective output current through a corresponding one of the plurality of LED driver circuits. A comparison circuit is coupled to the current to voltage converter circuit to compare the plurality of voltage signals. An adjustment circuit is coupled to the comparison circuit and the plurality of LED driver circuits. The adjustment circuit is configured to trim the plurality of LED driver circuits in response to the comparison circuit such that each respective output current through the plurality of LED driver circuits is substantially equal.

A current matching circuit includes a plurality of LED driver circuits. A current to voltage converter circuit is coupled to the plurality of LED driver circuits to generate a plurality of voltage signals. Each one of the plurality of voltage signals is representative of a respective output current through a corresponding one of the plurality of LED driver circuits. A comparison circuit is coupled to the current to voltage converter circuit to compare the plurality of voltage signals. An adjustment circuit is coupled to the comparison circuit and the plurality of LED driver circuits. The adjustment circuit is configured to trim the plurality of LED driver circuits in response to the comparison circuit such that each respective output current through the plurality of LED driver circuits is substantially equal.

A power converter and method for improving the current control stability of power converter by balancing the secondary winding currents is provided herein. The power converter includes a primary circuit having switches controllably driven at an operating frequency to produce an AC output through a primary transformer winding, and a secondary circuit having first and second secondary windings having respective leakage inductances. The secondary circuit provides power at an output node based on a power transfer between the primary winding and the first and second secondary windings. At least one balance inductor is coupled in series with the first and second secondary windings, and configured to reduce a difference between the first leakage inductance and the second leakage inductance. The at least one balance inductor may further be configured to reduce a difference between first and second AC current peaks associated with the first and second secondary windings, respectively.

A power converter and method for improving the current control stability of power converter by balancing the secondary winding currents is provided herein. The power converter includes a primary circuit having switches controllably driven at an operating frequency to produce an AC output through a primary transformer winding, and a secondary circuit having first and second secondary windings having respective leakage inductances. The secondary circuit provides power at an output node based on a power transfer between the primary winding and the first and second secondary windings. At least one balance inductor is coupled in series with the first and second secondary windings, and configured to reduce a difference between the first leakage inductance and the second leakage inductance. The at least one balance inductor may further be configured to reduce a difference between first and second AC current peaks associated with the first and second secondary windings, respectively.

The invention concerns a lighting arrangement having at least two light strings, each light string comprising at least one optoelectronic component configured for a power consumption in operation of more than 8 W. A couple of adjustable current sources are connected to a respective one of the at least two light strings and configured to provide an adjustable supply current to respective one of the at least two light strings. The arrangement further comprises an AC/DC converter utilizing GaN based FET technology configured to provide a DC supply voltage to the at least two adjustable current sources and the respective light strings connected thereto. Finally, a control circuit is coupled to the at least two adjustable current sources and configured to individually adjust a duty cycle for each of the at least two adjustable current sources and the supply current provided by the at least two adjustable current sources.

The invention concerns a lighting arrangement having at least two light strings, each light string comprising at least one optoelectronic component configured for a power consumption in operation of more than 8 W. A couple of adjustable current sources are connected to a respective one of the at least two light strings and configured to provide an adjustable supply current to respective one of the at least two light strings. The arrangement further comprises an AC/DC converter utilizing GaN based FET technology configured to provide a DC supply voltage to the at least two adjustable current sources and the respective light strings connected thereto. Finally, a control circuit is coupled to the at least two adjustable current sources and configured to individually adjust a duty cycle for each of the at least two adjustable current sources and the supply current provided by the at least two adjustable current sources.

A drive circuit includes a plurality of capacitors; a plurality of first interrupters configured to select paths through which electric charges are supplied to the plurality of capacitors; and a plurality of second interrupters configured to select paths through which the plurality of capacitors supply electric charges to a plurality of light emitting elements. In a case where the first interrupters are controlled and an electric charge is stored in a capacitor corresponding to one light emitting element included in the plurality of light emitting elements to selectively turn on the one light emitting element, at least while an electric charge is supplied to a light emitting element to be turned on, one second interrupter coupled to a path through which an electric charge is supplied to a light emitting element not to be turned on interrupts the path.

The invention provides a retrofit LED lamp driver having a shunt switch to alternately shunt (for a first duration) and not shunt (for a second duration) received AC power. The first duration is concurring with a first polarity of each AC cycle of the AC power, for a first period comprising at least one AC cycle, and the first duration is concurring in a second, opposite polarity of the AC power, for a second period comprising another at least one AC cycle not overlapping with the first duration. Alternating the first and second periods are provided. Any DC offset in the current drawn caused by the shunting operation is thereby cancelled over time.

The invention provides a retrofit LED lamp driver having a shunt switch to alternately shunt (for a first duration) and not shunt (for a second duration) received AC power. The first duration is concurring with a first polarity of each AC cycle of the AC power, for a first period comprising at least one AC cycle, and the first duration is concurring in a second, opposite polarity of the AC power, for a second period comprising another at least one AC cycle not overlapping with the first duration. Alternating the first and second periods are provided. Any DC offset in the current drawn caused by the shunting operation is thereby cancelled over time.

An LED lighting apparatus includes a first LED light source and a second LED light source included in a first light source group; a third LED light source and a fourth LED light source included in a second light source group; a mode detection circuit configured to determine a mode; a current control unit for serial and parallel connection of the first light source group and the second light source group; balancing circuits for serial and parallel connection of the respective light source groups; and a current path providing circuit for providing current paths. The LED lighting apparatus performs light emission in various states depending on the change of a rectified voltage and the change of a mode.