Test results

AN2590

12/17

Figure 15 shows the voltage and current waveform of the boost inductor L1. The glitch

could happen while L1 works in two directions at critical conduction mode.

Although the glitch was there, due to the limitation of maximum Ton, the power factor is

always higher than 0.8 in operating range. Please refer to Figure 16 below.

Figure 16.

Power factor in operating range

The different Ton to triac in the dimming control circuit provides the different power

dissipation to the lamp. The figures also show the negative resistance characteristics of the

lamp, such as when the lamp current decreases, the voltage increases accordingly.

Figure 17, shows us the voltage and current measurement at Ton equal to 9 ms. Figure 18,

shows us the voltage and current measurement at Ton equal to 5 ms. Figure 19 shows us

the voltage and current measurement at Ton equal to 3 ms.

Figure 14.

AC input voltage and current

Figure 15.

L1 voltage and current