Abstract: A method for driving and dimming an HID lamp (2), the method comprising the steps of: providing a controllable HBCF current source stage (20); using the HBCF current source stage (20) to generate commutating DC lamp current (I) having alternating current direction; supplying the HBCF current source stage (20) with an intermediate voltage (Vo). In normal mode, the commutating DC lamp current (I) is generated with a predetermined nominal current magnitude (IN) while the intermediate voltage (Vo) has a predetermined nominal level (VN). In a dim mode, the commutating DC lamp current (I) is generated with a current magnitude lower than said nominal current magnitude (IN) while the intermediate voltage (Vo) has a level (VH) higher than said nominal level (VN).

Abstract: A driver (10) for driving a gas discharge lamp (11) comprises at least two controllable switches (M1, M2) and a controller (12) for controlling the switches. The controller has a first operative state in which one switch (M1) is conductive while the other switch (M2) is non-conductive, and has a second operative state in which said other switch (M2) is conductive while said first switch (M1) is non-conductive. The controller comprises a memory device (20) comprising a plurality of memory elements (21) each containing a binary value (“0”; “1”), wherein the value of the last memory element (21(N)) determines the operative state of the controller. Responsive to a clock signal (SQL) generated by a clock device (30), the memory device shifts the contents of each memory element (21(i)) to a subsequent memory element (21(i+1)) and shifts the contents of the last memory element (21(N)) to the first memory element (21(1)).

Abstract: A method of electronic ballast protection including providing an electronic ballast having an AC/DC converter 104 with an electronic ballast input and a mains voltage connection 103 connectable to a mains voltage 102, an inverter 120 operably connected to the AC/DC converter 104 and having an electronic ballast output 125 connectable to a lamp 124, a control circuit 116 controlling the inverter 120, and a low voltage power supply 114 providing low voltage power to the control circuit 116; supplying power to the low voltage power supply 114 from the electronic ballast input when the mains voltage connection 103 is wired to mains voltage 102; and disconnecting the power to the low voltage power supply 114 when the electronic ballast output 125 is wired to the mains voltage 102.

Abstract: A circuit arrangement for operating a high pressure discharge lamp comprises a down converter equipped with an output capacitor and a commutator equipped with lamp connection terminals. The amplitude of the DC current generated by the down converter is controlled by means of a control loop. Commutation of the DC current causes a periodical voltage to be present across the output capacitor. This periodical voltage can be an overshoot voltage and/or a voltage caused by resonance of the lamp with the output capacitor. To suppress the periodical voltage, the reference signal of the current control loop is adjusted in dependency of the amplitude of the periodical voltage.

Abstract: A method of electronic ballast protection including providing an electronic ballast having an AC/DC converter 104 with an electronic ballast input and a mains voltage connection 103 connectable to a mains voltage 102, an inverter 120 operably connected to the AC/DC converter 104 and having an electronic ballast output 125 connectable to a lamp 124, a control circuit 116 controlling the inverter 120, and a low voltage power supply 114 providing low voltage power to the control circuit 116; supplying power to the low voltage power supply 114 from the electronic ballast input when the mains voltage connection 103 is wired to mains voltage 102; and disconnecting the power to the low voltage power supply 114 when the electronic ballast output 125 is wired to the mains voltage 102.

Abstract: A driver for HID lamps includes four switches and generates a constant DC-current that is commutated at a low frequency. The driver includes a filter capacitor. The occurrence of peak currents due to the charging or discharging of the filter capacitor is prevented by driving one of the switches at a high frequency immediately after commutation.

Abstract: A circuit arrangement for operating a high pressure discharge lamp comprises a down converter equipped with an output capacitor and a commutator equipped with an ignition choke. The amplitude of the DC current generated by the down converter is controlled by means of a control circuit. To suppress resonance of the ignition choke with the output capacitor caused by commutation of the DC current, the current reference signal of the current control is adjusted in dependency of the power consumed by the lamp and in dependency of the lamp voltage immediately before and after each commutation.