| 摘要 |
An electronic ballast for supplying a lamp load is described. The electronic ballast comprises an inverter arranged in a half-bridge configuration for providing an AC voltage and at least one lamp load circuit. The inverter comprises an upper switch, connected to a DC terminal for receiving a DC supply voltage, and a first lower switch arranged in a half-bridge configuration for generating an AC voltage at an inverter terminal of the inverter. A first diode and a second lower switch are connected in series. This series arrangement is connected in parallel with the first lower switch. A lamp load circuit for supplying the lamp load is connected to a node between the first diode and the second lower switch. When the inverter supplies a fluorescent lamp, and the lamp load circuit comprises a heating circuit for heating an electrode of the fluorescent lamp, the heating circuit includes a heating transformer and a second lower switch connected in parallel with the primary winding of the transformer. By doing so, the heating circuit can be operated and controlled independent of the current supplied to the fluorescent lamp, or operating conditions of the fluorescent lamp.
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