AN4077 datasheet(19/33 Pages) STMICROELECTRONICS

19 / 33 page

AN4077

Test results and significant waveforms

Doc ID 022997 Rev 1

19/33

Because the brownout thresholds in the L6564H are internally fixed, the startup and

shutdown threshold can be adjusted slightly modifying the resistor values used for the MULT

pin. In

Figure 24 a startup tentative below the startup threshold is captured. As seen, at

startup the brownout function does not allow the PFC startup even if the VCC has reached

the L6564H turn-on threshold.

Figure 25 and 26 the circuit waveforms during brownout protection operation are

captured. In both cases the mains voltages were increased or decreased slowly: as can be

seen, at turn-on or at turn-off there are no bouncing or starting attempts by the PFC

converter.

Figure 27 and 28 the waveforms during the startup of the circuit at mains plug-in are

reported. Note that the VCC voltage rises up to the turn-on threshold, and the L6564H starts

Figure 24.

EVL6564H-100W startup attempt at 80 Vac-60 Hz-full load

AM11518v1

Figure 25.

EVL6564H-100W startup with slow

input voltage increasing-full load

Figure 26.

EVL6564H-100W turn-off with slow

input voltage decreasing-full load

AN4077 Datasheet(PDF) 19 Page - STMicroelectronics