Test results and significant waveforms

AN3065

14/33

Doc ID 16279 Rev 2

In

Figure 16 and 17 the detail of the waveforms at switching frequency shows the operation

of transition-mode control. Once the inductor has transferred all the stored energy, a falling

edge on the ZCD pin (pin #11) is detected and it will trigger a new on-time by setting the

gate drive high. As soon as the current signal on the CS pin (pin #4) reaches the level

programmed by the internal multiplier circuitry according to the input mains instantaneous

voltage and the error amplifier output level, the gate drive is set low and MOSFET

conduction is stopped. A following off-time will transfer the energy stored in the inductor into

the output capacitor and to the load. At the end of the current conduction a new

demagnetization will be detected by the ZCD that will provide for a new on-time of the

MOSFET.

Figure 14.

EVL6563H 100W TM PFC: Vds and

inductor current at 230 Vac, 50 Hz,

full load

Figure 15.

EVL6563H 100W TM PFC: Vds and

inductor current at 230 Vac, 50 Hz,

full load (detail)

CH4: Q1 drain voltage

CH2: MULT voltage - pin #3

CH1: L2 inductor current

CH4: Q1 drain voltage

CH2: MULT voltage - pin #3

CH1: L2 inductor current