Abstract: An apparatus for delivering power to a load, which comprises a power converter that converts input power at a primary side to an output power and to a supply voltage to a secondary side. On the secondary side, a load switch is located on a current path to the load. A secondary-side control circuitry controls the load switch to operate in an ON mode in which current is provided to the load, and in response to a fault condition corresponding a voltage drop across the load switch exceeding a threshold value, activates circuitry on the secondary side. The circuitry, in response to the fault condition, causes the primary-side control circuitry to limit an extent to which the power converter is capable of supplying power.

Abstract: A secondary side controller for a power converter configured to provide a control signal to an emitter element of an opto-coupler for control of a primary side controller of the power converter, the secondary side controller configured to operate with the primary side controller for controlling the voltage output of the power converter, the secondary side controller configured to, based on; a first control value configured to instruct the power converter to output its present voltage output; and a second control value configured to instruct the power converter to provide a requested target voltage output; provide said control signal in accordance with a transition profile over a predetermined transition time period to effect a change between the first control value and the second control value, the transition profile comprising at least a first rate of change in the control signal followed by an end time period leading to the end of the transition time period during which the rate of change in the control

Abstract: An electronic ballast for lighting applications is disclosed. The electronic ballast comprises a first charge pump having an input capacitor (13) charged with a supply current drawn from a power source by application of a charging voltage to the input capacitor (13), the magnitude of the supply current being proportional to the magnitude of the charging voltage; and a voltage booster (16, 17) for generating a boost voltage, which is used to augment the charging voltage, thereby increasing the current drawn from the power source.

Abstract: A switching circuit and a method of operating the same are disclosed. In an embodiment, the switching circuit includes a switching transistor adapted to control operation of the switching circuit according to a control signal applied to the control terminal of the switching transistor, a regulating circuit adapted to generate the control signal, and a detecting circuit adapted to sense a voltage at the control terminal when the switching transistor is in an OFF state and to generate a drive signal according to the sensed voltage. The regulating circuit is adapted to generate the control signal based on the generated drive signal.

Abstract: A switched mode power supply (SMPS) controller is disclosed. The controller comprises a monitoring circuit adapted to monitor the rate of change of a voltage at an input (1) and to monitor the drop in voltage at the input (1) from a peak value. The controller is adapted to generate a signal for closing the switch when the monitored rate of change falls below a first predetermined threshold and the monitored drop in voltage exceeds a second predetermined threshold.

Abstract: A switching circuit (400) comprising an inductive component (406) including at least one winding; and a switch (404) is configured to transfer power from a voltage source (402) to the inductive component (406) in accordance with a switch control signal (412). The switching circuit (400) also comprises a controller (408) configured to integrate the voltage across the inductive component (406) in order to generate a signal representative of magnetic flux in the inductive component (406); and use the signal representative of the magnetic flux in the inductive component to account for a peak magnetization current value in order to control the switch (404).

Abstract: The invention relates to a control circuit (250) for a power supply unit (200) that has an input (207, 209) for receiving a mains supply (208), the control circuit (250) configured to: sample the input (207, 209) in order to obtain a first sample value; sample the input (207, 209) in order to obtain a second sample value subsequent to obtaining the first sample value; compare the first and second sample values to provide an outcome; set a delay interval in accordance with the outcome of the comparison of the first and second sample values; and sample the input (207, 209) in order to obtain a third sample value after the delay interval has elapsed.

Abstract: A surge protection circuit is disclosed for an electrical Load which may be for instance an LED load which is directly connected to a supply such as mains supply, and comprises a plurality of switches which are distributed across a plurality of semiconductor die. A surge detector detects the start of a spike in the supply, which results from, for example the commencement or interruption of a nearby inductive load, and opens all the switches. By distributing the switches across multiple die the peak voltage across each is reduced relative to using a single die; thereby each die can stay within the absolute maximum voltage capacity. Each die may have its own surge detector; alternatively, a single surge detector may be used which communicates with the switches on each of the die. In an extension the bridge rectifier may be integrated into the circuit distributed across the die. In this embodiment additional inter-die clamping diodes are required to prevent unsafe floating of the edge connections of each die.

Abstract: A switching circuit and a method of operating the same. The switching circuit comprises: a switching transistor adapted to control operation of the switching circuit according to a control signal applied to the control terminal of the switching transistor; a regulating circuit adapted to generate the control signal; and a detecting circuit adapted to sense a voltage at the control terminal when the switching transistor is in an OFF state and to generate a drive signal according to the sensed voltage. The regulating circuit is adapted to generate the control signal based on the generated drive signal.

Abstract: The present invention relates to a dimmer control circuit (100) capable to detect whether a phase-cut dimmer is connected using an average signal (VDCI) derived from the mains voltage. The average signal (VDCI) or a signal (VDCI_ls) derived from (VDCI), ranging from a minimum value to a maximum value, is compared to a dimming threshold (Vdim_th) through a phase-cut detecting unit (20). The comparison result is used to control the state diagram of a dimmer control logic (40) by selecting the step dimming mode (STD) or the phase-cut dimming mode (PCD). The output (OUT) of a switching unit (30) is determined by the state diagram of the dimmer control logic (40) in such a manner that the phase-cut dimming mode (PCD) is prioritized above the step-dimming mode (STD) and the maximum level of the STD states is depending on the mains voltage and application adjustable.

Abstract: A switching circuit (400) comprising an inductive component (406) including at least one winding; and a switch (404) is configured to transfer power from a voltage source (402) to the inductive component (406) in accordance with a switch control signal (412). The switching circuit (400) also comprises a controller (408) configured to integrate the voltage across the inductive component (406) in order to generate a signal representative of magnetic flux in the inductive component (406); and use the signal representative of the magnetic flux in the inductive component to account for a peak magnetization current value in order to control the switch (404).

Abstract: An electronic ballast for lighting applications is disclosed. The electronic ballast comprises a first charge pump having an input capacitor (13) charged with a supply current drawn from a power source by application of a charging voltage to the input capacitor (13), the magnitude of the supply current being proportional to the magnitude of the charging voltage; and a voltage booster (16, 17) for generating a boost voltage, which is used to augment the charging voltage, thereby increasing the current drawn from the power source.

Abstract: A switched mode power supply (SMPS) controller is disclosed. The controller comprises a monitoring circuit adapted to monitor the rate of change of a voltage at an input (1) and to monitor the drop in voltage at the input (1) from a peak value. The controller is adapted to generate a signal for closing the switch when the monitored rate of change falls below a first predetermined threshold and the monitored drop in voltage exceeds a second predetermined threshold.

Abstract: The present invention relates to a dimmer control circuit (100) capable to detect whether a phase-cut dimmer is connected using an average signal (VDCI) derived from the mains voltage. The average signal (VDCI) or a signal (VDCI_ls) derived from (VDCI), ranging from a minimum value to a maximum value, is compared to a dimming threshold (Vdim_th) through a phase-cut detecting unit (20). The comparison result is used to control the state diagram of a dimmer control logic (40) by selecting the step dimming mode (STD) or the phase-cut dimming mode (PCD). The output (OUT) of a switching unit (30) is determined by the state diagram of the dimmer control logic (40) in such a manner that the phase-cut dimming mode (PCD) is prioritized above the step-dimming mode (STD) and the maximum level of the STD states is depending on the mains voltage and application adjustable.

Abstract: A method of controlling a Fluorescent Lamp (CFL) is disclosed, which enables the lamp to be dimmed during a quick-start mode in which the lamp current may be boosted. The method involves determining a boost value and a dimming value, and controlling the lamp power in dependence on the boost and dimming values. A dimming threshold may be set, below which (i.e. at dimmer output light levels) the boost function is disabled. Hysteresis may be included in the control, in order to avoid hopping between modes. A controller for use with a fluorescent lamp which is adapted to operate according to such a method and a fluorescent lamp using such a controller are also disclosed.

Abstract: A surge protection circuit is disclosed for an electrical Load which may be for instance an LED load which is directly connected to a supply such as mains supply, and comprises a plurality of switches which are distributed across a plurality of semiconductor die. A surge detector detects the start of a spike in the supply, which results from, for example the commencement or interruption of a nearby inductive load, and opens all the switches. By distributing the switches across multiple die the peak voltage across each is reduced relative to using a single die; thereby each die can stay within the absolute maximum voltage capacity. Each die may have its own surge detector; alternatively, a single surge detector may be used which communicates with the switches on each of the die. In an extension the bridge rectifier may be integrated into the circuit distributed across the die. In this embodiment additional inter-die clamping diodes are required to prevent unsafe floating of the edge connections of each die.

Abstract: A ballast arrangement is provided for igniting and operating a discharge lamp. The lamp is connected in a commutating bridge in series with an inductor and parallel to a capacitor. The inductor and the capacitor together form a resonance circuit. During ignition, the bridge is commutated at a comparatively high frequency that changes with respect to time. The series resonance circuit has a resonance frequency that is close to an odd harmonic of the comparatively high frequency.

Abstract: A power converter includes a control device (28) for a switching power converter (10), a switching power converter and a method of controlling a switch in a power converter for reducing audible noise. The power converter includes the control device (28) and at least one switch (26) for regulating the power conversion. The control device (28) includes a timer (45) for monitoring a switching frequency of the switch (26) to indicate when the frequency has dropped to a certain level, and a gate driving circuit (32) connected to the timer and arranged to regulate the switching of the switch in dependence of the indication from the timer, so that the frequency rises above the certain level in order to reduce generation of audible noise.

Abstract: A method for driving a gas discharge lamp (1) is described, wherein electric first DC power is provided at a relatively high voltage and a relatively low current. Said first power is converted down to second DC power at a relatively low voltage and a relatively high current. Said second power is fed to a gas discharge lamp, preferably via a commutator. The conversion of said first power to said second power is performed in at least two steps, a first one of such steps including the step of converting down said first power to an intermediate DC power at an intermediate DC voltage lower (VM) than said first DC voltage but higher than said second DC voltage. A downconverter device (30) for use in a driving apparatus (10) for a gas discharge lamp (1) is described. The downconverter device comprises at least two downconverter units (31, 32) connected in series, for converting down said intermediate DC power to said second power.

Abstract: The invention relates to a ballast arrangement for igniting and operating a discharge lamp. The lamp is connected in a commutating bridge in series with an inductor and in parallel with a capacitor. The conductor and the capacitor jointly form a resonance circuit during an ignition phase. The bridge is then commutated at a comparatively high frequency. After the ignition phase, the lamp reaches a run-up phase, leading to a stable-operation phase. In the stable-operation phase, the bridge is commutated at a low frequency. According to the invention, the commutation frequency is lowered in steps from the comparatively high frequency during the ignition phase to the low frequency of the stable-operation phase so as to optimize current supply during the run-up phase.