| 摘要 |
A dimmable LED power supply circuit arrangement is disclosed. The circuit arrangement includes a flyback converter coupled between an input for receiving a rectified alternating line voltage and an output providing power for at least one LED device. The flyback converter includes a transformer and a semiconductor switch for switching a primary current of the transformer. A current sensing unit provides a current sense signal dependent on the primary current. A control unit controls the switching operation of the semiconductor switch dependent on the rectified alternating line voltage and the current sense signal such that the flyback converter operates in a quasi-resonant mode of operation, whereby the current sense signal is compared with a time-varying reference signal representing the rectified alternating line voltage and whereby a switch-off time of the semiconductor switch is determined dependent on the comparison.
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