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 the same time. On DC input voltage, the frequency of the boost controller (21) is varied to reduce EMI. The ballast operates in bands (91, 92, 93) according to 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 i n load, the microprocessor (31) changes the frequency of the inverter, thereby reducing output power and gradually unloading the boos t circuit and maintaining power to the microprocessor.
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