Abstract: The invention relates to an electronic ballast, in which an internal converter S1, S2, C1 continues to operate in the event of a lamp failure. An auxiliary power supply from control circuits can thus be maintained.

Abstract: The invention relates to an electronic ballast for lamps having a converter, in which a switching transistor is protected against transient disturbances by a detection circuit C1, C2, R1, R2, D1-3, T1. In this case, the time derivative of the voltage is taken into consideration.

Abstract: A circuit for protection against impulse voltages includes an input with first and second input connections to which is coupled a voltage that is loaded with an impulse voltage and corresponds to the system voltage, an output with first and second output connections to which the unit to be protected is coupled, and a protective circuit coupled between the first and second input or output connections. The protective circuit has a limiting apparatus that limits the voltage to a prescribable value, and a switch that includes a switching element and a drive circuit, the switching element being a semi-conductor component. The switch is arranged in series with the limiting apparatus and switches on responsive to a first trigger criterion and off responsive to a second trigger criterion.

Abstract: Circuit arrangement for operating discharge lamps (LP), having the following features: A power factor correction device (PFC) provides an intermediate circuit voltage; an inverter (INV), which draws its power from the intermediate circuit voltage, outputs power to discharge lamps (LP). According to the invention, an oscillation of the power factor correction device (PFC) only takes place when it is started, by means of a starting device (TRG), by an oscillation of the inverter (INV). This provides cost-effective control of the sequences in the circuit arrangement.

Abstract: The current through the components of a half-bridge of an electronic ballast is intended to be limited during the starting phase. For this purpose, the gate of a half-bridge transistor (T2) is driven by a current limiting circuit (D1, D2, D3, T3, C3) in such a way that the current through the transistors (T1, T2) is limited during the starting phase, whereas it remains unlimited during the glow phase and burning phase of the lamp (LA).

Abstract: Circuit arrangement for operating discharge lamps (LP), having the following features: A power factor correction device (PFC) provides an intermediate circuit voltage; an inverter (INV), which draws its power from the intermediate circuit voltage, outputs power to discharge lamps (LP). According to the invention, an oscillation of the power factor correction device (PFC) only takes place when it is started, by means of a starting device (TRG), by an oscillation of the inverter (INV). This provides cost-effective control of the sequences in the circuit arrangement.

Abstract: Free-running half-bridge inverter (HP) for operating gas discharge lamps having a current transformer as a feedback device. The half-bridge transistors (T1, T2) are essentially voltage controlled transistors (MOSFET). The drive circuits (1, 2) for the half-bridge transistors (T1, T2) contain a voltage threshold value switch (D2, R2) which, on reaching its voltage threshold, essentially carries a current which is proportional to the load current of the half-bridge inverter (HB).

Abstract: Free-running half-bridge inverter (HP) for operating gas discharge lamps having a current transformer as a feedback device. The half-bridge transistors (T1, T2) are essentially voltage controlled transistors (MOSFET). The drive circuits (1, 2) for the half-bridge transistors (T1, T2) contain a voltage threshold value switch (D2, R2) which, on reaching its voltage threshold, essentially carries a current which is proportional to the load current of the half-bridge inverter (HB).