| 摘要 |
A dimmable electronic ballast for an HID lamp (50) includes a rectifier stag e for rectifying an AC input (10) and providing a rectified DC output (14), a power factor (20) correction stage for modifying a power factor of the AC input and for providing an increased voltage DC output from the rectified DC output, an electronic ballast control circuit (80) for providing a driving signal comprising a pulse train for controlling a switching operation of an output switch stage (940) driving the HID lamp; the output switch stage (40) having at least one electronic switching element coupled to the increased voltage DC output for providing a pulsed power signal to the HID lamp to pow er the lamp (50), the electronic ballast control circuit (80) having a feedback input comprising a signal related to the power dissipated by the HID lamp fo r maintaining the power at a desired level, the desired level being set by a dimming control input (82) to the electronic ballast control circuit (80). T he circuit provides high frequency power, typically above 50 kHz, to the HID la mp (50).
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