january 2015 docid023991 rev 1 1/37 37 AN4214 application note high power factor flyback converter using the l6564 harjeet singh introduction this application note describes the example of single stage high power factor (hpf) flyback topology using st?s l6564 pfc controller. the l6564 is a current mode pfc controller operating in transition mode (tm). the highly linear multiplier, along with a special correction circuit that reduces crossover distortion of the mains current, allows wide range mains operation with an extremely low thd, even over a large load range. the main drawback of such flyback topology with hpf is that it has significant magnitude of twice the mains frequency ripple at output dc voltage be cause there is no electrolytic capacitor after bridge rectification. but there are some applic ations like lighting for led driving, battery chargers, where ripple voltage is not a big conc ern, since in these applications the loads are mostly constant-current driven with acceptable ripple or any kind of load which is powered through followed dc-dc downstream converte rs connected to output of hpf flyback. the output voltage is controlled by means of a voltage mode error amplifier and an accurate (1% at tj = 25 c) internal voltage reference. the loop stability is optimized by the voltage feedforward function (1/v 2 correction), which in this ic uses a proprietary technique that considerably improves line transient response as well in case of both drops and surges (?bidirectional?) of the mains. in addition to overvoltage pr otection being capable of cont rolling the output voltage in the pfc stage during transient conditions, the ic al so provides protection against feedback loop failures or erroneous settings. the feature is qu ite useful in case of flyback operation to detect output voltage for any primary auxilia ry winding and trigge r the protection to shutdown the converter in case output voltage exceeds the nominal value. other on-board protection functions allow br ownout conditions and magnetic saturation to be safely handled. the brownout is sensed through the mult pin to shut down the converter in case the input mains supply drops below the minimum operating voltage level. the l6564 main features are: ? fast ?bidirectional? input voltage feedforward (1/v 2 correction) ? accurate adjustable outp ut overvoltage protection ? protection against feedback loop disconnection (latched shutdown) ? inductor saturation protection ? ac brownout detection ? low (100 a) start-up current ? 6 a max. operating bias current ? 1% (at t j = 25 c) internal reference voltage ? -600/+800 ma totem pole gate driver with active pull-down during uvlo ? ssop10 package www.st.com
contents AN4214 2/37 docid023991 rev 1 contents 1 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 smps description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1 pfc_ok . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1 pfc_ok function in pfc operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.2 pfc_ok function in flyback operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.3 vff pin and brownout function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 basic specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4 transformer construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5 test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6 waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 6.1 mains voltage and input current waveforms . . . . . . . . . . . . . . . . . . . . . . . 14 6.2 output load current waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6.3 steady state switching waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7 short-circuit test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8 no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9 harmonics measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 10 schematic of smps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 11 bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 12 cvcc controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 13 references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 14 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
docid023991 rev 1 3/37 AN4214 list of tables 37 list of tables table 1. basic specifications of smps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 table 2. transformer specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 table 3. winding details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 table 4. test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 table 5. bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 table 6. document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
list of figures AN4214 4/37 docid023991 rev 1 list of figures figure 1. block diagram of l6564 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 figure 2. output voltage setting, ov p and ffp functions: internal block diagram . . . . . . . . . . . . . . . 7 figure 3. input ovp protection network to bias pfc_ok . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 figure 4. voltage feedforward: squarer-divider (1/v 2 ) block diagram and transfer characteristic . . . . 9 figure 5. l6562a and l6564 comparison (package and features ) . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 figure 6. transformer construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 figure 7. current thd vs. mains voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 8. power factor vs. mains voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 9. full load efficiency vs. mains voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 10. ch: 4-input voltage; ch: 2-input current waveforms at 140 v ac . . . . . . . . . . . . . . . . . . . . . 14 figure 11. ch: 4-input voltage; ch: 2-input current waveforms at 190 v ac . . . . . . . . . . . . . . . . . . . . . 15 figure 12. ch: 4-input voltage; ch: 2-input current waveforms at 220 v ac . . . . . . . . . . . . . . . . . . . . . 15 figure 13. ch: 4-input voltage; ch: 2-input current waveforms at 265 v ac . . . . . . . . . . . . . . . . . . . . . 16 figure 14. ch: 2-output load current waveform at 220 v ac pk-pk current ripple = 112 ma . . . . . . . . . 17 figure 15. ch: 4-drain-source voltage; ch: 1-drain current; ch: 2-comp at 140 v ac . . . . . . . . . . . . . 18 figure 16. ch: 4-drain-source voltage; ch: 1-drain current; ch: 2-comp at 140 v ac (zoom view) . . . 18 figure 17. ch: 4-drain-source voltage; ch: 1-drain current; ch: 2-comp at 230 v ac . . . . . . . . . . . . . 19 figure 18. ch: 4-drain-source voltage; ch: 1-drain current; ch: 2-comp at 230 v ac (zoom view) . . . 19 figure 19. ch: 4-drain-source voltage; ch: 1-drain current; ch: 2-comp at 265 v ac . . . . . . . . . . . . 20 figure 20. ch: 4-drain-source voltage; ch: 1-drain current; ch: 2- comp at 265 v ac (zoom view) . . 20 figure 21. output short-circuit at 140 v ac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 22. output short-circuit at 140 v ac (zoom view 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 23. output short-circuit at 140 v ac (zoom view 2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 24. output short-circuit at 230 v ac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 figure 25. output short-circuit at 230 v ac (zoom view 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 figure 26. output short-circuit at 230 v ac (zoom view 2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 figure 27. output short-circuit at 265 v ac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 figure 28. output short-circuit at 265 v ac (zoom view 1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 figure 29. output short-circuit at 265 v ac (zoom view 2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 figure 30. no load waveforms at 140 v ac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 figure 31. no load waveforms at 265 v ac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 figure 32. current thd at 150 v ac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 figure 33. current thd at 190 v ac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 figure 34. current thd at 230 v ac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 figure 35. current thd at 265 v ac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 figure 36. schematic of smps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 figure 37. sea05 internal circuit and it s application in flyback topology . . . . . . . . . . . . . . . . . . . . . . . 34 figure 38. sea05 package and pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
docid023991 rev 1 5/37 AN4214 block diagram 37 1 block diagram figure 1. block diagram of l6564 $ 0 y 9 ) ) 6 5 4 6 7 $ 5 7 ( 5 / ( % 4 9 2 / 7 $ * ( 5 ( * 8 / $ 7 2 5 8 9 / 2 9 0 8 / 7 , 3 / , ( 5 ? , q w h u q d o 6 x s s o \ % x v 9 r o w d j h u h i h u h q f h v 9 f f * ' & |