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VK05CFL

Figure 3: Start-up phase

From figure 4 it can be observed that the value of secondary voltage decreases when the lamp current

increases. This happens because increasing the value of the current flowing through the tube, increase

the drop on it, consequently decreasing the voltage on the ballast inductor Lp and thereby decreasing also

the secondary voltage.

By inserting the filters (R4-C10; R5-C11) between the two secondary windings and the devices, it is

possible to guarantee a higher voltage on the input pin of the devices for longer time compared to the

secondary signal. In this way it is possible to extend the use of the VK05CFL to all the power range eg.5W

– 23W.

Figure 4: Steady state waveforms

midpoint

diac