Patent ID: 8120270
Filing Date: 2012-02-21
Classification: H05B

Abstract:
1. A circuit arrangement for operating a discharge lamp with preheatable electrodes comprising: an input terminal for applying an input voltage; an output terminal for providing an output voltage to a lamp generator for operating the discharge lamp; a switching unit for power factor correction which is coupled between the input terminal and the output terminal; a monitoring apparatus which is adapted to switch off the lamp generator in the event of the presence of at least one switch-off criterion; an integrated circuit, which is adapted to drive the switching unit for power factor correction, the integrated circuit having a disable input; and a blocking apparatus, which is adapted to generate a blocking signal at its output when the lamp generator is switched off, the output of the blocking apparatus being coupled to the disable input of the integrated circuit, wherein the lamp generator has a trapezoidal capacitor, and the blocking apparatus generates the blocking signal based on a characteristic of a voltage at the trapezoidal capacitor.