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AN829 APPLICATION NOTE

CONCLUSIONS

This paper presents an optimized Power Factor Corrector built around a power module driven by the L4981 con-

trol IC. This STE36N50-DK ISOTOP power module is mounted directly on the PCB providing both very low in-

ductance layout and compact hardware.

Eliminating parasitic inductances enables tight control of switching di/dt and prevents turn off overvoltage.

Therefore faster switching speeds are allowed to reduce switching losses. The 2Amps current capability of the

controller is also a useful feature.

Combined with a single layer winding inductor, such a configuration results in very low EMI and RFI generation.

Finally, there is potential for further improvements using two features of the L4981:

– the possibility either to synchronize the IC with an external signal, or to modulate the PFC switching

frequency to spread the RFI noise.

– the extra multiplier input, which enables external compensation.