AN3065 datasheet(17/33 Pages) STMICROELECTRONICS

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AN3065

Test results and significant waveforms

Doc ID 16279 Rev 2

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Figure 21 shows the circuit behavior in case of a mains dip. As previously described, the

internal circuitry has detected the decreasing of the mains voltage and it has activated the

CFF internal fast discharge. As visible, in that case the output voltage changes but in few

mains cycles it comes back to the nominal value. The situation is different if we check the

performance of a controller without the VFF function. Figure 20 shows the behavior of a PFC

using the L6562A delivering similar output power. In case of a mains dip from 140 Vac to 90

Vac, the output voltage variation is not very different, but the output voltage requires a longer

time to restore the original value.

Testing with a wider voltage variation (e.g. 265 Vac to 90 Vac), the output voltage variation of

a PFC without the voltage feed-forward fast discharge is emphasized even more.

Figure 20.

L6562A input mains dip 140 Vac to

90 Vac, no VFF input

Figure 21.

EVL6563S-100W TM PFC: input

mains dip 140 Vac to 90 Vac

CH1: Vout

CH2: MULT (pin #3)

CH4: I_AC

CH1: Vout

CH2: MULT (pin #3)

CH3: VFF (pin #5)

CH4: I_AC

AN3065 데이터시트(PDF) 17 Page - STMicroelectronics