|
If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
Datasheet File OCR Text: |
february 2011 doc id 18376 rev 1 1/47 AN3329 application note 170 w power supply with pfc an d standby supply for flat tv using the l6564, l6599a, and viper27ln introduction this application note describes the characteristics and features of a 170 w, wide input mains range, power-factor-corrected, demonstration board for flat tvs or industrial applications. the electrical specificatio ns are tailored to a typical flat tv. the architecture is made up of three stages: a front-end pfc pre-regulator based on the l6564 tm (transition mode) boost pfc controller and a downstream llc resonant half bridge converter stage, built around the new l6599a resonant controller, which provides two regulated output voltages at 12 v and 24 v. in addition, a flyback-based standby supply delivers 10 w to a 5 v output. thanks to the chipset used, this design achieves very high efficiency, compliant with energy star ? eligibility criteria (epa rev. 2.0 eps), as well as very low input consumption during standby operation. figure 1. evl170w-ftv: 170 w demonstration board www.st.com
contents AN3329 2/47 doc id 18376 rev 1 contents 1 main characteristics and cir cuit description . . . . . . . . . . . . . . . . . . . . . 6 2 efficiency measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3 harmonic content measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4 functional check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5 conducted emission pre-compli ance test . . . . . . . . . . . . . . . . . . . . . . 29 6 bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 7 pfc coil specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 8 resonant power transformer speci fications . . . . . . . . . . . . . . . . . . . . 41 9 auxiliary flyback transformer specifications . . . . . . . . . . . . . . . . . . . . 43 10 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 AN3329 list of tables doc id 18376 rev 1 3/47 list of tables table 1. overall efficiency measured at different ac input voltages . . . . . . . . . . . . . . . . . . . . . . . . . 9 table 2. bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 table 3. pfc coil winding data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 table 4. resonant transformer winding data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 table 5. dc output voltage and load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 table 6. standby transformer winding data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 table 7. document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 list of figures AN3329 4/47 doc id 18376 rev 1 list of figures figure 1. evl170w-ftv: 170 w demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 figure 2. electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 figure 3. overall efficiency vs. output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 4. average efficiency acc. es-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 5. standby supply efficiency vs. output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 6. standby supply efficiency vs. light load output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 7. en61000-3-2 compliance at 230 vac - 50 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 figure 8. jeita-miti compliance at 100 vac - 50 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 figure 9. en61000-3-2 compliance at 230 vac - 50 hz, 75 w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 figure 10. jeita-miti compliance at 100 vac - 50 hz, 75 w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 figure 11. input voltage and current at 100 vac, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 12. input voltage and current at 230 vac, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 13. standby supply waveforms at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 14. standby supply waveforms at 230 vac - 50 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 15. standby supply waveforms at 400 vdc, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 16. standby supply output rectifiers piv at 400 vdc, full load . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 17. standby supply 5 v ripple at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 18. standby supply startup at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 19. standby supply burst mode operation at 230 vac - 50 hz - 10 ma load . . . . . . . . . . . . . . 15 figure 20. standby supply burst mode operation at 230 vac - 50 hz - 10 ma load-detail . . . . . . . . . 15 figure 21. standby supply ovp at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 figure 22. standby supply ovp at 230 vac - 50 hz - 0.5 a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 figure 23. standby supply ovp at 115 vac - 60 hz - pfc on - 1 a . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 24. standby supply ovp at 115 vac - 60 hz - pfc on - 1 a . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 25. standby supply output short-circuit at 230 vac - 50 hz, full load . . . . . . . . . . . . . . . . . . . . 16 figure 26. standby supply output short-circuit at 230 vac - 50 hz, full load - detail . . . . . . . . . . . . . . 16 figure 27. standby supply dynamic load at 115 vac - 60 hz - pfc off . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 28. standby supply dynamic load at 115 vac - 60 hz - pfc on . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 29. pfc vds and inductor current at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . 18 figure 30. pfc vds and inductor current at 115 vac - 60 hz, full load - detail . . . . . . . . . . . . . . . . . . 18 figure 31. pfc vds and inductor current at 230 vac - 50 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 32. pfc vds and inductor current at 230 vac - 50 hz, full load - detail . . . . . . . . . . . . . . . . . . 19 figure 33. l6564 signals-1 at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 34. l6564 signals-2 at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 35. pfc signals-1 at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0 figure 36. pfc signals-2 at 115 vac - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0 figure 37. resonant stage waveforms at 115 v - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 38. resonant stage waveforms at 115 v - 60 hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 39. output rectifiers piv waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 40. no load operation at 115 vac - 60 hz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 41. no load operation at 115 vac - 60 hz - l6599a signals . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 42. 12 v - 2 a; 24 v 0 6 a transition at 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 figure 43. 24 v - 6 a; 12 v 0 2 a transition at 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 figure 44. 12 v - 2 a; 24 v 0 6 a - 300 hz transition at 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . 24 figure 45. 24 v - 6 a; 12 v 1 2 a - 300 hz transition at 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . 24 figure 46. 12 v short-circuit at full load and 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 figure 47. 12 v short-circuit at full load and 115 vac - 60 hz - detail . . . . . . . . . . . . . . . . . . . . . . . . . 25 figure 48. 24 v short-circuit at full load and 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 figure 49. 24 v short-circuit at full load and 115 vac - 60 hz - detail . . . . . . . . . . . . . . . . . . . . . . . . . 25 AN3329 list of figures doc id 18376 rev 1 5/47 figure 50. startup by on-off signal at full load and 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . . . . . . 26 figure 51. startup by on-off signal at full load and 1 15 vac - 60 hz - l6599a signals . . . . . . . . . . . . 26 figure 52. startup by on/off signal at full load and 115 vac - 60 hz o/p voltage rising . . . . . . . . . . . 27 figure 53. turn-off at full load and 115 vac - 60 hz by on/off signal . . . . . . . . . . . . . . . . . . . . . . . . . . 27 figure 54. ovp at full load and 115 vac - 60 hz on 12 v - 24 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 figure 55. ovp at full load and 115 vac - 60 hz on 12 v - 24 v - outputs detail . . . . . . . . . . . . . . . . 27 figure 56. half cycle mains dip at full load and 115 vac - 60 hz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 figure 57. full cycle mains dip at full load and 115 vac - 60 hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 figure 58. ce peak measurement at 115 v - 60 hz and full load - phase wire . . . . . . . . . . . . . . . . . . 29 figure 59. ce peak measurement at 115 v - 60 hz and full load - neutral wire . . . . . . . . . . . . . . . . . 29 figure 60. ce peak measurement at 230 v - 50 hz and full load - phase wire . . . . . . . . . . . . . . . . . . 30 figure 61. ce peak measurement at 230 v - 50 hz and full load - neutral wire . . . . . . . . . . . . . . . . . 30 figure 62. pfc coil electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 figure 63. pfc coil mechanical aspect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 figure 64. transformer overall drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 figure 65. transformer electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 figure 66. transformer construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 figure 67. mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 figure 68. mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 main characteristics and circuit description AN3329 6/47 doc id 18376 rev 1 1 main characteristics and circuit description the main features of the smps are: universal input mains range: 90 264 vac - frequency 45 65 hz output voltage 1: 24 v 5 % at 6 a for backlight and audio supply output voltage 2: 12 v 3 % at 2 a for tv panel supply output voltage 3: 5 v 2 % at 2 a for microprocessor supply mains harmonics: acc. to en61000-3 -2 class-d or jeita-miti class-d standby mains consumption: at 230 vac <150 mw with 50 mw load overall efficiency at full load: above 90 % emi: according to en55022-class-b safety: according to en60065 dimensions: 197x115 mm, 25 mm maximum component height from pcb pcb: single side, 70 m, cem-1, mixed pth/smt. the circuit is made up of two sections; a 10 w supply generating 5 v standby output, dedicated to supplying the tv microprocessor and the logic circuitry, and a larger section made up of a pfc front-end and an llc resonant converter which provides two output voltages, one dedicated to supplying the tv panel, and one for the backlight and audio power amplifiers. the pfc stage delivers 400 v constant voltage and acts as a pre- regulator for both the llc stage and the standby supply. an external signal, referred to as secondary ground, turns the pfc and llc stages on and off. startup at turn-on the standby supply starts up and delivers 5 v dedicated to the tv microprocessor and other logic circuitry. it also generates the aux iliary supply voltage for the pfc and llc controllers at primary side via the linear regulator q7. q7 is activated by the optocoupler u5, that is driven by the logic signal on/off (active high). at startup, the on/off signal (delivered by the microprocessor) is supposed to be low, so the pfc and the llc are off. once the on/off signal is asserted high, the regulator q7 prov ides 14 v to the l6564 pfc controller and the l6599a llc controller; to always ensure proper operation of the llc, the circuit is designed so that the pfc starts first, then the downstream converter. the line pin of l6599a allows the resonant stage to operate only if the pfc output is delivering its rated output voltage. it prevents the resonant converter from working with an input voltage that is too low which may cause the undesirable capacitive-mode operation. the l6599a line pin internal comparator has a hysteresis allowing to set the turn-on and turn-off thresholds independently. the llc turn-on voltage (pfc output) and the turn-off threshold are set to 380 v and 300 v respectively. this last value prevents the llc stage operating in capacitive-mode but allows the resonant stage to operate even in the case of mains sag or dips lowering the pfc output voltage. brownout protection brownout protection prevents the circuit from working with abnormal mains levels. it is accomplished by both the viper, through the brownout pin, and the l6564, through an internal comparator internally connected to the vff pin (#5), which detects the mains voltage peak value. the internal comparators allow the ic operation with proper mains level only, as defined by power supply specifications, therefore, if the input voltage is below around 80 vac (typ.), the circuit is not allowed to start up. AN3329 main characteristics and circuit description doc id 18376 rev 1 7/47 resonant power stage the downstream converter features the st l6599a, which embeds all the functions needed to drive properly the resonant converter with 50 % fixed duty cycle and variable frequency. the converter makes use of a transformer designed with the integrated magnetic approach, using the primary leakage as the resonant series inductance and the magnetizing inductance as the resonant shunt inductance. the transformer secondary-side is center- tapped and power schottky diodes are used as output rectifiers. additional lc filter stages have been added on each output to minimize high-frequency ripple. output voltage feedback loop the regulation feedback loop is implemented through a typical circuit using a tl431, which modulates the current through the optocoupler diode. in order to improve the cross regulation, the two resonant stage output voltages are regulated by a weighted feedback control, that is using a single rail to regulate multiple outputs. the feedback loop is closed to the primary side by r37, which connects the rfmin (#4) pin of the resonant controller l6599a to the optocoupler phototransistor and sets the maximum switching frequency at around 130 khz. this value has been chosen to limit the switching losses at light load operation. on the same pin, r36 connected to ground, sets the minimum switching frequency. the rc series r22 and c21 sets both soft-start maximum frequency as well as duration. l6599a overload and short-circuit protection half bridge primary-side current is sensed by th e lossless circuit consisting of r53, c36, d14, d12, r55, and c38 and is fed into the isen pin (#6). during an overcurrent event, the pin voltage rises to the internal comparator threshold (0.8 v), triggering the following protection sequence: the soft-start capacito r (c10) connected to the delay pin (#2) is charged by an internal 150 a current generator and is slowly discharged by the resistor r12. this pin is connected to the dis (#8) pin and, if the voltage reaches 1.85 v, the ic stops switching, being latched off. once latched, an on/off signal recycle is needed to restart the converter. overvoltage and open loop protection both pfc and resonant stages are provided with their own overvoltage protections. the pfc controller l6564 monitors its output voltage through the resistor divider connected to the pfc_ok pin (#6) protecting the circuit in case of loop failure, disconnection, or deviation from the nominal value of the feedback loop divider. when a fault condition is detected, the l6564 is shut down and latched off by an internal circuit monitoring the voltage on the pfc_ok and inv pins, until the mains volta ge is recycled. upon the occurrence of an overvoltage condition, of either the 24 v or 12 v output of the resonant stage, the zener diodes d16 and d17 conduct, respectively, forcing q10 to be turned on by the resulting base current, which causes q9 to conduct. these two transistors form a pnp-npn scr (silicon controlled rectifier) structure that shorts to ground the anode of the u5 optocoupler in such a way that the ic supply voltage vcc cannot be delivered to controllers by q7, forcing them to be latched off until the mains voltage is recycled. main characteristics and circuit description AN3329 8/47 doc id 18376 rev 1 figure 2. electrical diagram ! - v 6 a c 6 ! 6 ! / & |