AN3142 datasheet(37/44 Pages) STMICROELECTRONICS

No. de pieza	AN3142

Descripción Electrónicos	Solution for designing a 400 W fixed-off-time controlled

PDF	44 Pages

Scroll/Zoom	100%

Fabricante Electrónico	STMICROELECTRONICS [STMicroelectronics]

Página de inicio	http://www.st.com

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37 / 44 page

AN3142

L6563H: high voltage startup transition mode PFC

Doc ID 17005 Rev 3

37/44

Figure 25.

High-voltage startup managing the DC-DC output short circuit

Figure 25 shows how the PFC manages the Vcc cycling and the associated power transfer.

At short circuit the auxiliary circuit is no longer able to sustain the Vcc which starts dropping;

reaching its VccOFF threshold the IC stops switching, reduces consumption and drops more

until the Vccrestart threshold is tripped. Now, the high voltage startup generator restarts and

when the Vcc crosses its turn-on threshold again the IC starts switching. In this manner the

power is transferred from mains to PFC output only during a short time for each Trep cycle.

AN3142 Datasheet(PDF) 37 Page - STMicroelectronics