L6599AT

Application information

Doc ID 15534 Rev 3

17/31

no-load consumption of this stage (0.5 1 W). There is no compliance issue because EMC

regulations on low-frequency harmonic emissions refer to nominal load, so no limit is

imposed when the converter operates with light or no load.

To do so, the L6599AT provides pin 9 (PFC_STOP): it is an open collector output, normally

open, that is asserted low when the IC is idle during burst-mode operation. This signal is

externally used for switching off the PFC controller and the pre-regulator as shown in

Figure 9

. When the L6599AT is in UVLO the pin is kept open, to let the PFC controller start

first

Figure 8.

Load-dependent operating modes: timing diagram

Figure 9.

How the L6599AT can switch off a PFC controller at light load