Abstract: A switch mode power supply is described including a primary side for coupling to a mains supply and a secondary side for coupling to a device, an isolation transformer comprising a primary coil and a secondary coil and arranged to isolate the primary side from the secondary side, and a noise filter coupled between a primary ground at the primary side and a secondary ground at the secondary side, the noise filter having a conductance value that varies with frequency. The noise filter conductance comprises a peak conductance in a peak conductance frequency region. The noise filter is operable to reduce the common-mode noise of the switch mode power supply at frequencies occurring in the peak conductance frequency region.

Abstract: A wireless charging transmitter has a rectifier circuit, a transmitter coil, a transmitter coil driving circuit, and a control circuit. The rectifier circuit receives an alternating current (AC) mains input voltage and provides a rectified mains voltage. The transmitter coil is provided for inductively coupling with a receiver coil on a device having a battery to be charged. The transmitter coil driving circuit directly receives the rectified mains voltage, and for providing a time-varying driving signal to the transmitter coil. The control circuit is coupled to the transmitter coil to receive charging information from a receiver battery inductively coupled to the transmitter coil through load modulation. In response, the control circuit controls a frequency and duty cycle of the time-varying driving signal based at least in part on the charging information.

Abstract: A wireless charging transmitter has a rectifier circuit, a transmitter coil, a transmitter coil driving circuit, and a control circuit. The rectifier circuit receives an alternating current (AC) mains input voltage and provides a rectified mains voltage. The transmitter coil is provided for inductively coupling with a receiver coil on a device having a battery to be charged. The transmitter coil driving circuit directly receives the rectified mains voltage, and for providing a time-varying driving signal to the transmitter coil. The control circuit is coupled to the transmitter coil to receive charging information from a receiver battery inductively coupled to the transmitter coil through load modulation. In response, the control circuit controls a frequency and duty cycle of the time-varying driving signal based at least in part on the charging information.

Abstract: A switch mode power supply is described including a primary side for coupling to a mains supply and a secondary side for coupling to a device, an isolation transformer comprising a primary coil and a secondary coil and arranged to isolate the primary side from the secondary side, and a noise filter coupled between a primary ground at the primary side and a secondary ground at the secondary side, the noise filter having a conductance value that varies with frequency. The noise filter conductance comprises a peak conductance in a peak conductance frequency region. The noise filter is operable to reduce the common-mode noise of the switch mode power supply at frequencies occurring in the peak conductance frequency region.

Abstract: There is disclosed a driver for driving a series arrangement being a variable number of strings of LEDs wherein each string has a capacitance connected in parallel with the respective string; the driver comprising: a controllable current source adapted to be connected in series between the series arrangement and a rectified AC supply to and source a controllable current (Istr) through the series arrangement; and a current source controller adapted to control the controllable current source; wherein the current source controller is operable to source a relatively lower current (ILED?) when a difference (Vstr3A) between the voltage across the series arrangement and the voltage of the rectified AC supply is relatively higher and a relatively higher current (ILED) when the difference is relatively lower. Associated driver circuits and lighting circuits, and methods are also disclosed.

Abstract: There is disclosed a driver for driving a series arrangement being a variable number of strings of LEDs wherein each string has a capacitance connected in parallel with the respective string; the driver comprising: a controllable current source adapted to be connected in series between the series arrangement and a rectified AC supply to and source a controllable current (Istr) through the series arrangement; and a current source controller adapted to control the controllable current source; wherein the current source controller is operable to source a relatively lower current (ILED?) when a difference (Vstr3A) between the voltage across the series arrangement and the voltage of the rectified AC supply is relatively higher and a relatively higher current (ILED) when the difference is relatively lower. Associated driver circuits and lighting circuits, and methods are also disclosed.

Abstract: A circuit is disclosed for driving a plurality of LED strings from an AC supply and arranged to, in use, drive current through a series arrangement of a plurality N of the LED strings when the AC voltage is sufficient to drive the plurality N of the LED strings: the circuit comprising a first current source configured to be switchably connected to a one end of said series arrangement of N LED strings; a series combination of a second current source and a heat dissipater, wherein the series combination of the second current source and the heat dissipater is arranged in parallel with the first current source; and a current balancer for balancing the current through the first current source and the second current source. A driver for such a circuit is also disclosed.

Abstract: A control device (701) for controlling the output of one or more full-bridges (101, 102) is described. The control device (701) reduces the amount of electromagnetic emissions by staggering the switching the outputs from the full-bridge inverters (101, 102). This is achieved by synchronizing the outputs to be symmetrical about a synchronization pulse (305).

Abstract: A method of driving current from an AC power supply through a series arrangement of a varying number of strings of LEDs is disclosed, the method comprising, adding LED strings to the series arrangement in a first order during an increasing voltage part of a cycle of the AC power supply cycle and subsequently removing LED strings from the series arrangement in a second order s during a decreasing voltage part of the cycle, wherein the second order is not the reverse of the first order. A driver for operating such a method is also disclosed, as is an IC embodying such a driver.

Abstract: A drive circuit for delivering an AC voltage to an array of electro-luminescent lamps (8a to 8n) includes a single coil (1), the energy in which is transferred to each lamp through a corresponding switch assembly (10a to 10n) having positive and negative-going paths for conducting positive and negative voltages to the corresponding lamp. The magnitudes of the voltages applied to the parallel-connected lamps are controllable so that the illumination levels of the lamps are individually adjustable.

Abstract: A drive circuit for delivering an AC voltage to an array of electro-luminescent lamps (8a to 8n) includes a single coil (1), the energy in which is transferred to each lamp through a corresponding switch assembly (10a to 10n) having positive and negative-going paths for conducting positive and negative voltages to the corresponding lamp. The magnitudes of the voltages applied to the parallel-connected lamps are controllable so that the illumination levels of the lamps are individually adjustable.

Abstract: A control device (701) for controlling the output of one or more full-bridges (101, 102) is described. The control device (701) reduces the amount of electromagnetic emissions by staggering the switching the outputs from the full-bridge inverters (101, 102). This is achieved by synchronising the outputs to be symmetrical about a synchronisation pulse (305).

Abstract: Ballast circuit for operating a gas discharge lamp, comprising a half-bridge DC-AC converter having a voltage controlled oscillator (VCO) for alternately switching the switches (T1; T2) of said half-bridge, said oscillator (VCO) having an input with a control voltage (V vco) which determines the operating frequency of said half-bridge, a resonance circuit connected to said half-bridge for feeding the lamp, and a feedback circuit connected at a first end to said resonance circuit for adjusting the operating frequency of said half-bridge, wherein the other end of said feedback circuit is connected to the input of said voltage controlled oscillator (VCO) and designed such that during at least a substantial part of the start-up period of the lamp an equilibrium exists wherein the half-bridge frequency is at least nearly equal to the resonance frequency and the half-bridge voltage is forced to operate at least nearly in phase with the half-bridge current.

Abstract: Ballast circuit for operating a gas discharge lamp, comprising a half-bridge DC-AC converter having a voltage controlled oscillator (VCO) for alternately switching the switches (T1; T2) of said half-bridge, said oscillator (VCO) having an input with a control voltage (V vco) which determines the operating frequency of said half-bridge, a resonance circuit connected to said half-bridge for feeding the lamp, and a feedback circuit connected at a first end to said resonance circuit for adjusting the operating frequency of said half-bridge, wherein the other end of said feedback circuit is connected to the input of said voltage controlled oscillator (VCO) and designed such that during at least a substantial part of the start-up period of the lamp an equilibrium exists wherein the half-bridge frequency is at least nearly equal to the resonance frequency and the half-bridge voltage is forced to operate at least nearly in phase with the half-bridge current.

Abstract: A power supply arrangement having a DC/DC converter is presented that includes a control loop on the primary side of the isolation transformer within the DC/DC converter to control the voltage on the primary winding. The energy transfer across the isolation transformer is effected via control switches that alternately charge and discharge a capacitor through the primary winding. The control loop preferably adjusts the duty cycle of these control switches to control the voltage on the primary winding.

Abstract: The invention relates to a power supply arrangement (2, 3) comprising a DC/DC converter (3) including:

Abstract: A power supply (10), comprising a rectifier (2) having an input side (3) connectable to an AC main power supply and an output side (6) connectable to a load; and a controllable shunt switch circuit (12), wherein the shunt switch circuit (12) is arranged on the input side (3) of the rectifier (2) to selectively shunt the rectifier (2) via the output side thereof.

Abstract: A pulse igniter for a discharge lamp has a transformer with a primary winding coupled to a first capacitor and a switching element and a secondary winding shunted by a series circuit of a diode and a second capacitor at its output. As a result, the generated ignition voltage is rectified and applied to the lamp for a relatively long time interval, resulting in improved ignition behavior.

Abstract: A DC/DC converter of the flyback/forward converter type includes a switch (S), a transformer (T), a first diode (D1), a first capacitor (C1), a second diode (D2) and a second capacitor (C2). The first and the second capacitor are arranged in series between the output terminals (K3, K4) of the DC/DC converter. The DC/DC converter has a high efficiency and is very suitable for operating a lamp with a DC current.

Abstract: A circuit arrangement for supplying a discharge lamp with a direct current includes input terminals for connection to a supply voltage source. A circuit portion (I) is coupled to the input terminals for generating a DC voltage from the supply voltage and is provided with output terminals between which the DC voltage is present during operation. A first branch comprising a first capacitor interconnects the output terminals and a second branch comprising a series arrangement of a second capacitor and an impedance shunts the first branch. A load branch shunts the series arrangement and comprises terminals for connecting a discharge lamp. The second branch also includes a diode so that a discharge lamp operated by way of the circuit arrangement stabilizes satisfactorily after ignition by a current supplied by the second capacitor to the lamp via the impedance.