| 摘要 |
A ballast having a detection circuit for detecting characteristics of at least two different voltages supplied to independent input terminals of the ballast, wherein the detection circuit comprises a rectifying unit 1 that comprises a first input terminal for applying a first externally supplied voltage (VAC1) and a second externally supplied voltage (VAC2), wherein the first voltage (VAC1) is a switched AC and the second voltage (VAC2) is an AC voltage. The detection circuit further comprises an evaluating unit (2), which is configured to provide a detection signal that indicates whether the first voltage (VAC1) is present; and whether the second voltage (VAC2) is present or replaced by a DC voltage. The rectifying unit 1 may comprise a single full wave rectifier for rectifying both the first voltage (VAC1) and the second voltage (VAC2). The first voltage may be fully rectified by means of the full wave rectifying unit 12 and the second voltage may be half rectified by a sub section of the full wave rectifier 11. |
