| 摘要 |
2103542 9216085 PCTABS00016 A voltge boost power supply, for use in a fluorescent lamp ballast (100), having: an inductance (170) coupled between an alternating supply voltage input (108, 110) and an output (134, 136), a switch (128) for controlling the current carried by the inductance, and a current-mode control IC (144) for producing a PWM control signal to control the switch so as to control the current carried by the inductance and thereby control the voltage across the inductance. The current-mode control IC is coupled (138) to the input so that the frequency of the control signal is modulated in accordance with the alternating supply voltage whereby the frequency of the control signal has a maximum value when the magnitude of the alternating supply voltage is a maximum. The power supply thus exhibits reduced harmonic distortion and increased power factor.
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