| 摘要 |
A microprocessor controlled, electronic ballast operates a lamp at nominal settings and shifts the operation of the ballast away from nominal settings to reduce interference. The shift is randomized by a test - flip - [shift] routine that prevents all ballasts from attempting the same correction at th e same time. On DC input voltage, the frequency of the boost controller (21) i s varied to reduce EMI. The ballast operates in bands (91, 92, 93) according t o the input voltage. Some bands correspond to full brightness, some to a fixed amount of dimming, and some to a variable amount of dimming. In the event of an abrupt change in load, the microprocessor (31) changes the frequency of t he inverter, thereby reducing output power and gradually unloading the boost circuit and maintaining power to the microprocessor.
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