DocID028175 Rev 3

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L6599AF

Application information

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eliminating the no load consumption of this stage (0.51 W). There is no compliance issue in

that, because EMC regulations on low-frequency harmonic emissions refer to nominal load,

no limit is envisaged when the converter operates with light or no load.

To do so, the L6599AF 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 L6599AF 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 L6599AF can switch off a PFC controller at light load