EVL6564-50WFLB Datasheet, PDF (3/6 Pages) STMicroelectronics – 50 W wide-range high power factor flyback converter demonstration board based on the L6564

EVL6564-50WFLB
General information and electrical schematic
regardless of mains voltage. Moreover, the L6564, offers a better immunity against external
noise thanks to the characteristics of its OVP function (without current OVP) and a
dedicated function to manage the burst mode condition is even available.
On the secondary stage, the dividers R26, R28 and R42, are dedicated to sensing the
output voltage. Capacitor C17 and diodes D7 and D8 provide a soft-start at turn-on. The
output regulation is done by means of an isolated voltage loop by the opto-coupler U1 and
using an inexpensive TS2431A (U4) to drive it. The opto-transistor modulates the input
voltage of the L6564 internal amplifier via R31 and R35. R21, R25 and C21 close the
voltage loop. The output rectifier is a fast recovery type, selected according to the maximum
reverse voltage, forward voltage drop and power dissipation. A small LC filter has been
added on the output, filtering the high frequency ripple.
Doc ID 023237 Rev 1
3/6