Test results and significant waveforms

AN3119

12/32

Doc ID 16849 Rev 2

load range during operation at low mains. THD increases and PF decreases during

European mains operation at light load because the circuit begins working in burst mode to

maintain good efficiency, preventing from operating at a too high switching frequency. In a

case where the burst mode operation cannot be accepted a compromise with efficiency

must be found. The burst mode threshold can be slightly adjusted by modifying the multiplier

divider ratio and/or the compensation network.

The measured efficiency is shown in Figure 13, measured according to the ES-2

requirements. It is excellent at all load and line conditions; at full load it is always higher than

94 %, making this design suitable for high efficiency power supply. The average efficiency

calculated according to the ES-2 requirements at different nominal mains voltages is shown

in Figure 14.

Figure 11.

EVL6563S-250W TM PFC: power

factor vs. output power

Figure 12.

EVL6563S-250W TM PFC: THD vs.

output power

Figure 13.

EVL6563S-250W TM PFC:

efficiency vs. output power

Figure 14.

EVL6563S-250W TM PFC: average

efficiency acc. to ES-2