Abstract: Various embodiments may relate to a circuit arrangement and a method for operating and dimming at least one LED. In this case, the LEDs are supplied from a bridge arrangement, wherein, in order to dim the at least one LED, the frequency of the control signals is increased with increasing dimming until a predefinable dimming threshold value. In order to adjust dimming values which are below the predefinable dimming threshold value, the output signal of the bridge arrangement is short-circuited by means of a short-circuit device during predefinable periods.

Abstract: Various embodiments may relate to a circuit arrangement and a method for operating and dimming at least one LED. In this case, the LEDs are supplied from a bridge arrangement, wherein, in order to dim the at least one LED, the frequency of the control signals is increased with increasing dimming until a predefinable dimming threshold value. In order to adjust dimming values which are below the predefinable dimming threshold value, the output signal of the bridge arrangement is short-circuited by means of a short-circuit device during predefinable periods.

Abstract: Various embodiments relate to a circuit arrangement for operating at least one discharge lamp. In order to prevent intrinsic flicker at low dimming settings and low temperatures, according to various embodiments, a direct current which is fed into the discharge lamp so as to avoid striated discharges at relatively high dimming settings is reduced or entirely eliminated.

Abstract: A method for operating a lamp, wherein in the preheating phase a first value of the voltage drop correlated with the reciprocal of the electrical resistance of a coil of the lamp is determined across a resistor at a first instant, and a second value of the voltage drop is determined at a second instant, may include: a) determining the difference between a first and the second value; b) b1) if the difference is greater than a first threshold value: carrying out an algorithm for lamp-type recognition; b2) if the difference is not greater than the first threshold value: c1) if the difference is greater than a second threshold value: d1) if the second value is greater than a third threshold value: determining a coil short circuit; d2) if the second value is not greater than the third threshold value: operating the lamp with the current set of operating parameters.

Abstract: A circuit arrangement for operating at least one discharge lamp may include: a first and a second input terminal for connecting a supply voltage; an inverter, which includes at least one first switch and one second switch, which are coupled in series between the first and the second input terminal and between which a bridge center point is defined; a drive circuit for at least the first switch and the second switch with an input for receiving a control signal; an apparatus for generating an auxiliary voltage.

Abstract: Various embodiments relate to a circuit arrangement for operating at least one discharge lamp. In order to prevent intrinsic flicker at low dimming settings and low temperatures, according to various embodiments, a direct current which is fed into the discharge lamp so as to avoid striated discharges at relatively high dimming settings is reduced or entirely eliminated.

Abstract: A method for operating a lamp, wherein in the preheating phase a first value of the voltage drop correlated with the reciprocal of the electrical resistance of a coil of the lamp is determined across a resistor at a first instant, and a second value of the voltage drop is determined at a second instant, may include: a) determining the difference between a first and the second value; b) b1) if the difference is greater than a first threshold value: carrying out an algorithm for lamp-type recognition; b2) if the difference is not greater than the first threshold value: c1) if the difference is greater than a second threshold value: d1) if the second value is greater than a third threshold value: determining a coil short circuit; d2) if the second value is not greater than the third threshold value: operating the lamp with the current set of operating parameters.

Abstract: A circuit arrangement for operating at least one discharge lamp may include: a first and a second input terminal for connecting a supply voltage; an inverter, which includes at least one first switch and one second switch, which are coupled in series between the first and the second input terminal and between which a bridge center point is defined; a drive circuit for at least the first switch and the second switch with an input for receiving a control signal; an apparatus for generating an auxiliary voltage.

Abstract: A method for operating at least one low-pressure discharge lamp having heatable lamp electrodes, in which, during the preheating phase of the lamp electrodes, the type of lamp is identified. In this case, the temperature dependence of the electrical resistance of the lamp electrodes is exploited.

Abstract: A method for operating at least one low-pressure discharge lamp having heatable lamp electrodes, in which, during the preheating phase of the lamp electrodes, the type of lamp is identified. In this case, the temperature dependence of the electrical resistance of the lamp electrodes is exploited.

Abstract: The invention relates to a microcontroller (MC) having at least one device (G) for generating pulse-width modulated or frequency modulated control signals for a switched-mode power supply. The device (G) has a further device (SQ1, SS1) for the alternate charging and discharging an electric charge store (C27) that can be connected to the microcontroller (MC), control means for this device (SQ1, SS1) for controlling the charging and discharging operations, and an evalutor for evaluating the time periods which are needed for the individual charging and discharging operations to generate pulse-width modulated or frequency modulated control signals. The microcontroller (MC) generates finely graduated, frequency modulated or pulse-width modulated control signals which are independent of the operating cycle frequency of the microcontroller (MC).

Abstract: The invention relates to a microcontroller (MC) having at least one device (G) for generating pulse-width modulated or frequency modulated control signals for a switched-mode power supply. According to the invention, this device (G) has a device (SQ1, SS1) for the alternate charging and discharging of an electric charge store (C27) that can be connected to the microcontroller (MC), control means for this device (SQ1, SS1) for controlling the charging and discharging operations, and evaluation means in order to evaluate the time periods which are needed for the individual charging and discharging operations; to generate pulse-width modulated or frequency modulated control signals. The microcontroller (MC) according to the invention generates finely graduated, frequency modulated or pulse-width modulated control signals which are independent of the operating cycle frequency of the microcontroller (MC).

Abstract: An integrated control and regulating circuit (IC) controls, via a half-bridge circuit (V2, V3), a load circuit (4) having the at least one fluorescent lamp (FL) by means of a drive circuit (CCO, SEL, HSD, LSD) regulated in a high-frequency manner. In the control and regulating circuit, each time the lamp is started and/or when there is a disturbance, a timer (PST, IT, CT) is started, which thus defines a sequence predetermined periods of time (&Dgr;pt, &Dgr;it, &Dgr;st, &Dgr;ot), inter alia preheating period (&Dgr;pt) and ignition period (&Dgr;it).

Abstract: A circuit arrangement used with electronic ballast equipment has an inverter which supplies a high-frequency half-bridge voltage to at least one load circuit having a lamp throttle, a fluorescent lamp, an ignition capacitor, and a half-bridge capacitor. In order to pre-heat the coils of the fluorescent lamp in a short period of time, a switchable voltage source is activated. This voltage source is connected to the output of the inverter. The outputs of the voltage source are constructed as a pair, to which the electrodes and the fluorescent lamp are connected in parallel. This voltage source includes a transformer having a primary winding coupled to the inverter and is switched between non-conducting and conducting (energized) states by a switching stage. The secondary windings of the transformer are connected in parallel to the electrodes of the fluorescent lamp.

Abstract: The method operates at least one fluorescent lamp (FL) using an electronic ballast. The ballast has a rectifier bridge (GL) which has AC mains voltage (L, N) across it, a connected step-up converter (L1, D1, V1), a half-bridge circuit (V2, V3) as well as a control loop (IC) for continuously monitoring the lamp current by means of a controlled drive circuit (CCO, SEL, HSD, LSD) of the power transistors (V2, V3), which drive circuit keeps the lamp current constant during normal operation. A timer (PST, IT, CT), which is started in a defined manner each time the lamp is started or a disturbance is detected, generates as superordinate control a time base for a monitoring circuit (MON). The monitoring circuit evaluates the instantaneous lamp current using predetermined reference levels (Mp, Mi and Mo) which vary in individual time segments (.DELTA.pt, .DELTA.it, .DELTA.st, .DELTA.

Abstract: Electronic ballasts are essentially composed of a series connection of a harmonic filter that has its input side connected to the AC line, a rectifier and an inverter to which is connected at least one load circuit composed of a series circuit of an inductor and a parallel circuit composed of a fluorescent tube and a capacitor. When a high electric tolerance is required of such a ballast in view of a desired increase in the power factor, standard circuit designs required a relatively expensive storage capacitor that smooths the AC rectified line voltage. In order to be able to use a storage capacitor that has a lower electric tolerance in comparison to the required voltage tolerance of the ballast, a storage capacitor is incorporated into one of the two capacitor branches of the inverter which is composed of a switch bridge arrangement having two switch branches and two capacitor branches, this storage capacitor being connected in series with the actual load.

Abstract: A shut-off device is provided for an inverter which feeds at least one discharge lamp, the shut-off device operable to shut-off the inverter in limiting cases and remaining in this condition until a lamp replacement. The shut-off device flips into its normal condition when a holding current in a monitoring circuit falls below a flyback limit value. In order to keep the losses as low as possible, the monitoring circuit is dimensioned high-resistant and a separate holding circuit is provided, the separate holding circuit having a controlled dependency on the low control current in the monitoring circuit. In the disconnect case, the control current also suffices to hold the shut-off device in the disconnect condition when an electrode is broken.

Abstract: In an inverter controlled with a firing unit connected to switches and defining an operating frequency, a resonant frequency of a series oscillating circuit of the inverter connected to one of the switches is placed below this operating frequency. Given this operating situation, a short of the d.c. voltage source is impossible. Given, for example, unfavorable component tolerances, however, the operating frequency can be moved close to the resonant frequency and cause impermissibly high voltages at the components. Such a voltage rise is limited according to the invention by means of a voltage-dependent resistor. It preferably lies in series with a capacitor and takes care of a voltage-dependent shift of the resonant frequency.

Abstract: An inverter with a dc-source has a charging condenser connected through a charging diode and a charging inductor to the dc-supply. A charging switch is periodically closed by a control component with a variable keying ratio to connect the charging inductor to the dc-supply. The inverter includes an AC voltage converter with two alternatingly controlled switches supplied with power by the charging condenser, hereinbelow identified as the primary switch and the secondary switch, which are in a series circuit in parallel with the charging condenser. In this arrangement, the control component for the charging switch of the charging regulator is synchronized with a square wave voltage at one of the switches of the alternating voltage converter. The charging switch operates at the same switching frequency as the alternating voltage converter.