AN2941 datasheet(16/37 Pages) STMICROELECTRONICS

16 / 37 page

Functional check

AN2941

16/37

Doc ID 15447 Rev 4

Functional check

The following figures show some flyback waveforms during steady-state operation and the

L6563S TBO function is depicted, setting different PFC output voltages according to the

mains input voltage.

At nominal load conditions, in Figure 9 and Figure 10, we note that the ZCD negative-going

edge triggers the MOSFET's turn-on, allowing quasi-resonant operation.

Figure 11

and Figure 12 show operation at 20 W. As indicated before, maximum switching

frequency has been set at 125 kHz. For this reason, the L6566A skips the first valley signal

on ZCD and switches on the MOSFET at the second negative-going edge.

Figure 9.

Flyback stage waveforms

at 115 V-60 Hz - full load

Figure 10.

Flyback stage waveforms

at 230 V -50 Hz - full load

CH1: Drain voltage

CH2: CS pin voltage

CH3: ZCD pin

CH4: PFC output

CH1: Drain voltage

CH2: CS pin voltage

CH3: ZCD pin

CH4: PFC output

Figure 11.

Flyback stage waveforms

at 115 V-60 Hz - 20 W load

Figure 12.

Flyback stage waveforms

at 230 V -50 Hz - 20 W load

CH1: Drain voltage

CH2: CS pin voltage

CH3: ZCD pin

CH4: PFC output

CH1: Drain voltage

CH2: CS pin voltage

CH3: ZCD pin

CH4: PFC output

AN2941 Datasheet(PDF) 16 Page - STMicroelectronics

AN2941 Datasheet(HTML) 16 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Datasheet Download

Link URL