| 摘要 |
A ballast ( 10 ) for powering at least one gas discharge lamp ( 40 ) includes an EMI filter ( 100 ), a full-wave rectifier ( 200 ), a DC-to-DC converter ( 300 ), an inverter ( 400 ), an output circuit ( 500 ), and a microcontroller ( 600 ). In response to an output ground-fault condition wherein at least one output terminal ( 502,504,506,508 ) of the ballast ( 20 ) is shorted to earth ground, the microcontroller ( 600 ) directs the DC-to-DC converter ( 300 ) to remain in a non-operating mode wherein the output voltage of the DC-to-DC converter ( 600 ) is substantially zero, thereby protecting the inverter ( 400 ) from damage. Preferably, the microcontroller ( 600 ) monitors a voltage across a DC blocking capacitor ( 530 ) within the output circuit ( 500 ) prior to startup of the DC-to-DC converter ( 300 ) in order to determine if an output ground-fault condition is present.
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