| 摘要 |
A circuit arrangement for operating at least one low-power lighting unit with a phase-cut operating voltage from a power supply is disclosed, which circuit arrangement comprises a serial setup of an input device (6), a two-port power shaping circuit (7, 7′, 7″) and a lamp driver unit (8, 8′, 8″). The power shaping circuit (7, 7′, 7″) comprises at least a bleeder (13) and a damping circuit (14). While the bleeder circuit (13) provides an alternative current path to set a global current, drawn during operation from the power supply to a predefined minimum load current, the damping circuit (14) serves to attenuate high frequency oscillations in said operating voltage. To enhance dimmer compatibility and simultaneously provide a cost-efficient circuit setup, a first and a second feedback circuit (18, 25) is provided, allowing to control the bleeder circuit (13) and the lamp driver unit (8, 8′, 8″) according to a two-point control. |
| 主权项 |
1. Circuit arrangement for operating at least one low-power lighting unit with a phase-cut operating voltage from a power supply, comprising
an input device for connection to said power supply having at least a first and second supply terminal, a two-port power shaping circuit, with at least
a first and a second input terminal, connected with the respective supply terminals of said input device,a first and second output terminal, connected with said input terminals over first and second supply connections,a controllable bleeder circuit, connected with said first and second input terminals to provide an alternative current path between said input terminals and being configured to set a global current, drawn during operation from the power supply to a predefined minimum load current, anda damping circuit, connected to said first and second supply connections at a first and a second connection point to attenuate high frequency oscillations in said operating voltage, and a lamp driver unit, connected to at least one of the output terminals of the power shaping circuit and being configured for connection to said at least one low-power lighting unit, said lamp driver unit comprising at least a lamp current controller, configured to set a lamp current of said at least one low-power lighting unit and a first feedback circuit, configured to provide a first feedback signal, corresponding to the momentary lamp current of said at least one low-power lighting unit, wherein the lamp current controller is connected with said first feedback circuit to control the lamp current in dependence of said feedback signal, so that the lamp current corresponds to a setpoint current, wherein the controllable bleeder circuit is configured to set the global current to the predefine minimum load current independently of the control of the lamp current. |
