 The EVAL6574B is a board made to help the evaluation of the L6574. It is composed of two sections: the PFC, using the L6562 controller, and the ballast, based on the L6574. The design has been developed to drive a TL fluorescent lamp up to 58W from an AC mains voltage that can range from 85V to 265V.
The turn-on sequence is divided in three phases: preheating, ignition and normal lamp burning. The application is provided with a current feedback, that allows power control (and in case the dimming function) by varying the switching frequency during the normal lamp burning. The application is also provided with two safety circuitries. The first one acts in case of lamp disconnection to prevent capacitive mode. The second alarm has been designed to protect the application against the extra voltages which would arise if the lamp does not strike after the ignition sequence, because it is an old lamp.
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