| 摘要 |
Light from a fluorescent lamp 230 is dimmed by modulating the width of current pulses. A current command signal is applied to a resonant bridge lamp driver 226 in response to a voltage-level corresponding to a given, selectable level of desired lamp brightness. The lamp driver operates as a flyback AC power source that advantageously uses a FET switch 222 to decouple the lamp and resonant bridge 226 from the current-sampling process. A resistor 232 only samples the current in an inductor 224 while the FET switch 222 is active. Because the current sample is decoupled from the lamp and bridge, particularly tight control of the regulation process is provided to control incoming noise and transients that affect the power supplied to the lamp, which may be used in a backit avionics display. The lamp driver can also operate as a synchronously driven resonant forward converter that senses the current actually supplied to the lamp and responds to changes in the lamp's condition (Fig Il).
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