AN3339 datasheet(19/44 Pages) STMICROELECTRONICS

Part #	AN3339

Description	185 W power supply with PFC and standby supply for LED TV

PDF	44 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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19 / 44 page

AN3339

Functional check

Doc ID 18449 Rev 2

19/44

Figure 29 and 30 show the PFC control signal; in particular the VFF signal which is the

second input to the multiplier for 1/V2 function. The voltage at this pin, a DC level equal to

the peak voltage on the MULT pin (#3), compensates the control loop gain line-dependence.

In Figure 30, it can be observed that a negative-going edge on the ZCD pin triggers the

MOSFET turn-on.

Figure 27.

PFC Vds and inductor current at

230 Vac - 50 Hz, full load

Figure 28.

PFC Vds and inductor current at

230 Vac, full load - detail

CH3: CS (pin #4)

CH1: Q1 drain voltage

CH2: MULT (pin #3)

CH4: L1 inductor current

CH3: CS (pin #4)

CH1: Q1 drain voltage

CH2: MULT (pin #3)

CH4: L1 inductor current

Figure 29.

L6564 signals (1) at 115 Vac - 60 Hz,

full load

Figure 30.

L6564 signals (2) at 115 Vac - 60 Hz,

full load

CH3: MULT (pin #3)

CH1: COMP (pin #9)

CH2: VFF (pin #7)

CH4: CS (pin #4)

CH3: MULT (pin #3)

CH1: GD (pin #9)

CH2: ZCD (pin #7)

CH4: CS (pin #4)

AN3339 Datasheet(PDF) 19 Page - STMicroelectronics