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october 2007 rev 1 1/33 an2521 application note 19 v - 75 w laptop adapter with tracking boost pfc pre-regulator, using the l6563 and l6668 introduction this application note describes the characteristics and features of a 75 w wide range input mains and power-factor-corrected ac-dc adapter evaluation board. its electrical specification is tailored to a typical high-end portable computer power adapter. the distinctive attributes of this design are the very low standby input consumption (< 0.3 w at 265 v), the excellent global efficiency (> 85%) for a two stage architecture and the low cost. figure 1. l6668 and l6563-75w adapter evaluation board (EVAL6668-75W) www.st.com
contents an2521 2/33 contents 1 main characteristics and cir cuit description . . . . . . . . . . . . . . . . . . . . . 4 2 test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1 efficiency measurements at full load, tracking boost option (tbo) . . . . . . 8 2.2 harmonic content measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3 functional check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.1 normal operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.2 standby and no-load operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.3 over current and short circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.4 overvoltage and open loop protection . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4 EVAL6668-75W: thermal map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.1 thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2 thermal map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5 conducted emission pre-compli ance test . . . . . . . . . . . . . . . . . . . . . . 22 6 bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 7 pfc coil specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.1 general description and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.2 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.3 electrical schematic and winding characterist ics . . . . . . . . . . . . . . . . . . . 28 7.4 mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 8 transformer specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8.1 general description and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8.2 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8.3 electrical diagram and winding characteristics . . . . . . . . . . . . . . . . . . . . . 30 8.4 mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 9 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
an2521 list of figures 3/33 list of figures figure 1. l6668 and l6563-75w adapter evaluation board (EVAL6668-75W) . . . . . . . . . . . . . . . . . . 1 figure 2. electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 figure 3. EVAL6668-75W global efficiency measurements at full load . . . . . . . . . . . . . . . . . . . . . . . . 8 figure 4. l6563 tracking boost and voltage feed-forward blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 figure 5. EVAL6668-75W pfc out put voltage vs. ac input volt age . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 6. pfc efficiency with and without tbo function at full load . . . . . . . . . . . . . . . . . . . . . . . . . 10 figure 7. flyback converter efficiency with and without tbo function at full load . . . . . . . . . . . . . . . 10 figure 8. comparison between the global efficiency with and without tbo . . . . . . . . . . . . . . . . . . . 11 figure 9. EVAL6668-75W comp liance to en61000-3- 2 standard @230 v, 50 hz - full load . . . . . . 11 figure 10. EVAL6668-75W co mpliance to jeida-miti st andard @100 v, 60 hz - full load . . . . . . . . 11 figure 11. EVAL6668-75W co mpliance to en61000-3-2 standard @230 v, 50 hz - half load . . . . . 12 figure 12. EVAL6668-75W co mpliance to jeida- miti standard @100 v, 60 hz - half load . . . . . . . 12 figure 13. EVAL6668-75W input current waveform @100 v, 60 hz - full load . . . . . . . . . . . . . . . . . . 12 figure 14. EVAL6668-75W input current waveform @230 v, 50 hz - full load . . . . . . . . . . . . . . . . . . 12 figure 15. EVAL6668-75W flyback stage waveforms @115 v, 60 hz-full load. . . . . . . . . . . . . . . . . . 13 figure 16. EVAL6668-75W flyback stage waveforms @230 v, 50 hz-full load. . . . . . . . . . . . . . . . . . 13 figure 17. adapter circuit primary side waveforms 265 v, 50 hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 18. eval6668-75 w no-load operat ion waveforms @90 v, 60 hz . . . . . . . . . . . . . . . . . . . . . 14 figure 19. eval6668-75 w no-load operat ion waveforms @265 v, 50 hz . . . . . . . . . . . . . . . . . . . . 14 figure 20. eval6668-75 w transition full lo ad-to-no load at 265 v, 50 hz . . . . . . . . . . . . . . . . . . . . . 15 figure 21. eval6668-75 w transition no l oad-to-full load at 265 v, 50 hz . . . . . . . . . . . . . . . . . . . . . 15 figure 22. eval6668-75 w short circuit at full load & 230 vac-50 hz . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 23. eval6668-75 w short circuit removal at full load & 230 vac-50 hz . . . . . . . . . . . . . . . . . 17 figure 24. eval6668-75 w short circuit at no-load & 230 vac-50 hz . . . . . . . . . . . . . . . . . . . . . . . . 18 figure 25. eval6668-75 w short circuit removal at no-load & 230 vac-50 hz. . . . . . . . . . . . . . . . . . 18 figure 26. EVAL6668-75W open loop at 115 vac-60 hz - full load . . . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 27. thermal map at 115 vac-60 hz - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 figure 28. thermal map at 230 vac-50 hz - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 29. ce peak measure at 100 vac and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 30. ce peak measure at 230 vac and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 figure 31. electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 figure 32. mechanical aspect and pin numbering of pfc coil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 figure 33. electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 figure 34. winding position on coil former. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 figure 35. mechanical aspect and pin numbering of flyback transformer . . . . . . . . . . . . . . . . . . . . . . 32
main characteristics and circuit description an2521 4/33 1 main characteristics and circuit description the main characteristics of the smps are listed here below: universal input mains range: 90 - 264 vac, 45 ? 65 hz output voltages: 19 v @ 4 a continuous operation mains harmonics: in accordance with en61000-3-2 class-d standby mains consumption: less than 0.3 w @ 265 vac overall efficiency: greater than 85% emi: in accordance with en55022-class b safety: in accordance with en60950 pcb single layer: single side, 70 m, cem-1, 78 x 174 mm, mixed pth/smt the circuit is made up of two stages: a front-end pfc using the l6563 and a flyback converter based on the l6668. the electrical schematic is shown in figure 2 . the flyback stage works as the master stage and therefore is dedicated to controlling circuit operation, including standby and protection functions. additionally, it switches the pfc stage on and off the by means of a dedicated pin on the control ic, thus helping to achieve good efficiency even at light load. the input emi filter is a classic pi-filter, 1-cell for differential and common mode noise. an ntc in series wit h the pfc output capacitor limits the inrush current produced by the charging of the capacitor at plug-in. the purpose of the pfc stage is to reduce the harmonic content of the input current to be within the limits imposed by european norm en61000-3-2. additionally, it provides a regulated dc bus used by the downstream converter. the pfc controller is the l6563 (u1), working in transition mode. it integrates all functions needed to control the pfc as well as an interface to the master converter. its power stage topology is a conventional boost converter, connected to the output of the rectifier bridge. it includes the coil l2, the diode d3, the capacitor c6 and the power switch q2, a power mosfet. the secondary winding of l2 (pins 8-3) provides the l6563 with information about the core demagnetization of the pfc coil, needed by the controller for tm (transition mode) operation. the divider r7, r12 and r18 provides the l6563 with the instantaneous input voltage information that is used to modulate the boost current, and to derive additional information such as the average value of the ac line, which is used by the v ff (voltage feed- forward) function. the divider r2, r6, r8, r9 is dedicated to sensing the output voltage and feeds the information to the error amplifier, while the divider r3, r5, r11, r19, directly connected to the output voltage, is dedicated to protecting the circuit in case of voltage loop failure. to maximize overall efficiency, the pfc makes use of the so-called "tracking boost option" (tbo). with this function implemented the dc output voltage of the pfc changes proportionally with the mains voltage. the l6563 achieves this functionality by adding a resistor (r30) connected to the dedicated tbo pin (#6). the pfc is switched on and off by a switch (q1) on the v cc pin of the l6563, which is activated by the pfc-stop pin of the l6668. the pfc-stop pin is intended to stop the pfc controller at light load by cutting its supply. this happens when the comp pin on the l6668 controller goes below 2.2v. the downstream converter, acting as the master stage, is managed by the l6668 ic (u2), a current mode controller. the 65 khz nominal switching frequency has been chosen to
an2521 main characteristics and circuit description 5/33 achieve a compromise between the transformer size and the harmonics of the switching frequency, thereby optimizing the input filter size and the total solution cost. the power mosfet is a standard, inexpensive 800 v component housed in a to-220fp package, requiring a small heat sink. the transformer is the layer type, using the standard ferrite core eer35. the transformer is manufactured by tdk and designed in accordance with en60950. the reflected voltage is ~130 v, providing sufficient room for the leakage inductance voltage spike while maintaining a ma rgin for the reliability of the power mosfet. the rectifier d8 and the transil d4 clamp the peak of the leakage inductance voltage spike at turn-off of the power mosfet. the controller l6668 offers maxi mum flexibility by integrating a ll the functionality needed for high performance smps control with a minimum component count. a new feature embedded in the device is a high voltage current source used at start-up which draws current directly from the dc bus and charges capacitor c33. after the voltage on c33 has reached the l6668 turn-on threshold and the circuit starts to operate, the controller is powered by the transformer via the auxiliary wi nding and diode d11. af ter start-up, the hv current source is deactivated, saving power during normal operation and allowing very good circuit efficiency during standby. the l6668 utilizes a cu rrent mode control system, so th e current flowin g through the primary winding is sensed by r52 and r53 and is then fed into pin #12 (isen). resistor r41 connected between pin #12 (isen) and pin #15 (s_comp) provides the correct slope compensation to the current signal, necessary fo r correct loop stability in ccm mode at duty cycles greater than 50%. the circuit connecte d to pin #7 (dis) provides over-voltage protection in case of feedback network failure, while the thermistor r58 provides for a thermal protection of the power mosfet (q5). this pin is also connected to the pwm_latch pin of the l6563 which is dedica ted to stopping activity of the flyback converter in case of pfc loop failure that could be damaging to the circuit. to definitively latch this state, the internal circuitry of the l6668 monitors the v cc and periodically reactivates the hv current source to supply the ic. after ovp detection and l6668 disable intervention, circuit operation can be resumed only after disconnection of the mains plug. the switching frequency is programmed by the rc connected to pin #16 (rct) and in case of reduced load operation the controller can decrease the operating frequency via pin #13 (stby) and resistor r42, proportionate with the load consumption. the resistor divider r60 and r61 connected to pin #9 (skipadj) allows setting of the initial l6668 threshold to burst mode functionality when the power supply is lightly loaded. additional functions embedded in the l6668 are the programmable soft-start and a 5 v reference, available externally. circuit regulation is achieved by modulating the voltage on the comp pin (#10), by means of the optocoupler u3. also connected to the comp pin is the q6, q8, r44, r62, c42 and d13 network, which is dedicated to driving isen over its hiccup mode threshold in case of overload or short condition. in this case th e device will be shut down and its consumption will decrease almost to pre-start- up level. the device will resume operation as soon as the v cc voltage has dropped below the v cc restart level. thus a reliable hiccup mode is invoked until the short is removed. a short on-time and long off-time of the hiccup mode are obtained allowing the average current flowing in the secondary side components to be kept at a safe level, avoiding consequent catastrophic failures due to their overheating. output regulation is done by means of two loops, a voltage and a current loop working alternately. a dedicated control ic, the tsm1014, has been used. it integrates two operational amplifiers and a precise voltage reference. the output signal of the error amplifiers drives optocoupler sfh617a-4 to transfer the information to the primary side and achieve the required insulation of the secondary side. the output rectifier d7 is a dual common-cathode schottky diode. the output rectifier has been selected according to the
main characteristics and circuit description an2521 6/33 calculated maximum reverse voltage, forward voltage drop and power dissipation. the snubber, made up of r14, r6 6 and c8, damps the oscillation produced by the diode d7. a small lc filter has been added on the output in order to filter the high frequency ripple.
an2521 main characteristics and circuit description 7/33 figure 2. electrical diagram g c34 100pf r3 2m2 r5 2m2 r11 2m2 c37 82n + _ ~ ~ d2 gbu4j c3 470nf-x2 c1 2n2 c2 2n2 c4 470nf-x2 l1 hf2826-253y 1r2-t01 r10 res f1 fuse 4a c40 100n c30 2n2-5% r42 8k2 c5 470n-400v l2 srw25cq-t03h102 d3 stth2l06 c23 res r1 ntc 10r-s236 c6 100uf-450v 15-16 5-6 2-3 10-11 r67 6k2-1% 19v@4a r33 10k r50 1k0 d7 stps20h100cfp r68 120k-1% 1 2 3 j1 input conn. c27 47uf-50v r41 10k r55 22r 90-264vac d4 1.5ke250a 1 2 jp7 res r72 0r0 r71 res d15 res q5 stp10nk80zfp r53 0r39 r52 0r39 r47 100k r46 47r r43 4r7 d12 ll4148 u4 ts3431iz-res r51 2k2 r37 10k-1% q3 res inv 1 comp 2 mult 3 cs 4 vff 5 tbo 6 pfc-ok 7 pwm-latch 8 pwm-stop 9 run 10 zcd 11 gnd 12 gd 13 vcc 14 u1 l6563 r61 33k r9 75k-1% t1 srw32ec-t01h114 r60 56k q2 stp9nk50zfp d1 1n4005 c38 470pf r7 3m3 c32 100n r12 3m3 c22 2u2-25v r18 51k r30 22k r26 120k r34 270k r27 0r33 hv 1 hvs 2 gnd 3 out 4 vcc 5 n.c. 6 dis 7 comp 10 ss 11 isen 12 stby 13 pfc_stop 14 s_comp 15 rct 16 vref 8 skip_adj 9 u2 l6668 r29 res r24 100k r23 27r r21 res r2 1m0-1% r6 1m0-1% d14 ll4148 r14 3r9 r8 75k-1% r59 24k r64 43k-1% r66 3r9 c19 2n2 c21 470n c25 220pf c26 22n c14 220n c20 10n c41 10n c9 100n c16 1000uf-25v zl c15 1uf r56 4k7-1% r17 62k r15 res r73 62k c39 4n7 c8 1n0-200v r57 100r q1 bc857c l3 tsl0706 - 1r5-4r3 r16 10k q4 res cv_out 5 cv- 4 v_ref 1 gnd 6 cc+ 3 cc- 2 cc_out 7 vcc 8 u5 tsm1014 c13 100uf-25v yxf r38 res c28 res q6 bc857c r54 47k r4 68k r28 2k2 c35 270n c17 100n d8 stth 108a r13 res c10 res r62 3k3 r20 20k c31 res r31 4k7 r45 2k2 c11 res c7 2n2 - y 2 r32 res 1 2 j2 con2-in r19 36k c33 22uf-50v d10 ll4148 d11 bav103 r35 2r7 d5 bzv55-b30 d13 ll4148 c42 10uf-50v r58 m57703 d6 res r25 470r r36 1k8 c24 2n2 - y 2 otp prot r69 1k0 d9 bzv55-c8v2 c36 100n q8 bc847c r39 56k-1% r48 4k7-1% r49 24k-1% r22 r015-1w - msr1 r40 res c29 res c12 1000uf-25v zl c44 100n 1 2 4 3 u3 sfh617a-4 r65 22k c43 2n2 r44 47k q7 res 6 5 3 8
test results an2521 8/33 2 test results 2.1 efficiency measurements at full load, tracking boost option (tbo) the following table and diagrams show the single converter and overall efficiency measured at different input voltages. these measurements are performed with nominal load (4 a). figure 3. EVAL6668-75W global efficiency measurements at full load in ta b l e 2 the energy star efficiency measurements are shown. the average of the two mains voltage inputs in four di fferent load conditions is complia nt with the target requirement (better than 84%). table 1. efficiency measurements at full load using the tbo function vin ac efficiency pfc dc-dc global 90 [v] 93.63% 89.83% 84.11% 115 [v] 95.62% 89.07% 85.17% (1) 1. compliant to cec, eu-coc, regulation. in table 1 and figure 3 the single converter efficiency measurement is shown. thanks to the very good efficiency of any single bl ock the overall e fficiency is very high too, especially if we compare this data with similar converters using a double stage and a flyback topology as downstream converter. 230 [v] 97.84% 89.81% 87.87% (1) 265 [v] 97.53% 89.06% 86.86% table 2. energy star compliance energy star efficiency vin ac 1 a 2 a 3 a 4 a average 115 [v] 85.26% 86.32% 86.28% 85.17% 85.75% 230 [v] 83.4% 85.2% 86.74% 87.87% 85.8% 80% 81% 82% 83% 84% 85% 86% 87% 88% 89% 90% 90 115 230 265 vin [vrms] overall efficiency with tbo
an2521 test results 9/33 to achieve optimal efficiency the pfc stage implements the tracking boost function. it consists of a pfc output voltage that follows the input voltage. typically, in traditional pfc stages, the dc output voltage is regulated at a fixed value (typically 400 volts) but in some applications, such as this one using a flyback as the downstream converter, it could be advantageous to regulate the pfc output voltage with the tracking boost or "follower boost" approach. in this way the circuit with the tbo function provides improved efficiency and, thanks to the lower differential voltage across the boost inductor, the value of l2 can be reduced as compared to the same circuit without the tbo function. in the present case a 400 h inductor has been used, while with a fixed output voltage pfc working at a similar operating frequency, a 700 h inductor is required. to achieve the tbo function on the l6563, a dedicated input of the multiplier is available on tbo pin #6. this function can be implemented by simply connecting a resistor (rt) between the tbo pin and ground. figure 4. l6563 tracking boost and voltage feed-forward blocks the tbo pin presents a dc level equal to the peak of the mult pin voltage and is then representative of the mains rms voltage. the resistor defines the current, equal to v(tbo)/rt, which is internally mirrored 1:1 and sunk from the inv pin (pin 1) input of the error amplifier. in this way, when the mains voltag e increases, the voltag e at the tbo pin will increase as well, and so will the current flo wing through the resistor connected between tbo and gnd. a larger current will then be sunk by the inv pin and th e output voltage of the pfc pre-regulator will be forced higher. obvi ously, the output vo ltage will move in the opposite direction if the input voltage decreases. to avoid an unwanted rise in output voltage should the mains voltage exceed the maximum specified value, the voltage at the tbo pin is clamped at 3 v. by properly selecting the multiplier bias it is possible to set the ma ximum input voltage above which input-to-output tracking ends and the output voltage becomes co nstant. if this function is not used, the pin should be left open; the device will regulate at a fixed output voltage. r1 l656 3 l656 3 a inv 1 vo u t tbo 6 1:1 current r t 2.5v e/a + - com 2 3 v - + 5 i tbo i r mul 3 r5 rectified m a in s r6 "ide a l" diode multiplier 1/v 2 c u rrent reference r2 i r i tbo 9 .5v 9 .5v vff c f r f
test results an2521 10/33 figure 5. EVAL6668-75W pfc output voltage vs. ac input voltage in figure 5 we can see that the pfc output voltage variation vs. the ac input voltage (i.e. the input voltage for the flyback stage) is dependent on the input mains voltage, but its range is narrower than a wide range input. thus the design of the flyback converter is not completely optimized as with a standard pfc delivering a stable 400 v output, but its design is much simpler than that of a wide range flyback. additionally, the pfc converter using the tbo, with its lower differential volt age across the inductor and lower current ripple, will have lower rms current and therefore better efficiency at low mains, where normally the efficiency of typical pfcs is lower. the result is a global efficiency of the circuit that will be higher than that of a fixed output voltage one circuit, especially at lower mains. most of the power dissipation will not be concentrated on the pf c only but will be shared with the flyback. therefore, there will not be ther mal hotspots and the reliability of the circuit will be improved. this is confirmed in the diagram in figure 6 , where the efficiency of the pfc has been measured both with the active tbo function and without it. as shown, at low input mains the circuit has an efficiency improvement better than 2 percent. as the input mains voltage increases the switching losses become more significant and the fixed output voltage pfc appears more efficient. using the tbo function even the flyback conver ter efficiency is very good, as shown in figure 7 where it is compared with the efficiency of the same converter powered by a fixed 218 242 351 384 186 219 252 285 318 351 384 417 80 130 180 230 280 vin [vrms] pfc output voltage [v] figure 6. pfc efficiency with and without tbo function at full load figure 7. flyback converter efficiency with and without tbo function at full load 90% 91% 92% 93% 94% 95% 96% 97% 98% 99% 100% 90 115 230 265 vin [vrms] pfc stage efficienc y without tbo with tbo 85% 86% 87% 88% 89% 90% 91% 92% 93% 94% 95% 90 115 230 265 vin [vrms] flyback stage efficienc y 400 vdc fixed i/p voltage with tbo
an2521 test results 11/33 400 v input voltage. it can be observed that an improvement is achieved at 90 vac and 230 vac mains. as a final measurement, the comparison betw een the global efficiency with and without tbo is shown in figure 8 , confirming the previous measurements. figure 8. comparison between the global efficiency with and without tbo 2.2 harmonic content measurement one of the main purposes of a pfc pre-conditioner is to correct the input current distortion, decreasing the harmonic contents below the limits of the relevant regulations. therefore, the board has been tested according to the european rule en61000-3-2 class-d and japanese rule jeida-miti class-d, at full load and 50% of output rated load, at both nominal input mains voltages. as demonstrated in the illustrati ons below, the circuit is capa ble of reducing the harmonics well below the limits of both re gulations from full load down to light load. because the maximum input power of the board is close to the limit of 75 w, to demonstrate the correct behavior of the circuit it has been tested also a 37 w (half load). of course, no current regulation requires meeting any limit at these power levels. 80% 81% 82% 83% 84% 85% 86% 87% 88% 89% 90% 90 115 230 265 vin [vrms] overall efficiency without tb o with tbo figure 9. EVAL6668-75W compliance to en61000-3-2 standard @230 v, 50 hz - full load figure 10. EVAL6668-75W compliance to jeida-miti standard @100 v, 60 hz - full load 0.0001 0.001 0.01 0.1 1 1 3 5 7 9 111315171921232527293133353739 harmonic order [n] harmonic current [a] measured value en61000-3-2 class-d limits 0.0001 0.001 0.01 0.1 1 1 3 5 7 9 111315171921232527293133353739 harmonic order [n] harmonic current [a] measured value jeida-miti class-d limits
test results an2521 12/33 on the bottom side of each diagram the total harmonic distortion and power factor have been measured as well. the values in all conditions give a clear idea of the correct functioning of the pfc even if the tracking boost option has been implemented. for user reference, input current and voltage waveforms at the nominal input mains voltages and full load are shown below. figure 11. EVAL6668-75W compliance to en61000-3-2 standard @230 v, 50 hz - half load figure 12. EVAL6668-75W compliance to jeida- miti standard @100 v, 60 hz - half load 0.0001 0.001 0.01 0.1 1 1 3 5 7 9 111315171921232527293133353739 harmonic order [n] harmonic current [a] measured value en61000-3-2 class-d limits 0.0001 0.001 0.01 0.1 1 1 3 5 7 9 111315171921232527293133353739 harmonic order [n] harmonic current [a] measured value jeida-miti class-d limits figure 13. EVAL6668-75W input current waveform @100 v, 60 hz - full load figure 14. EVAL6668-75W input current waveform @230 v, 50 hz - full load ch1: input mains voltage ch2: input mains current ch1: input mains voltage ch2: input mains current
an2521 functional check 13/33 3 functional check 3.1 normal operation figure 15 and figure 16 display some waveforms of the flyback stage during steady-state operation of the circuit at full load and nominal input voltage ranges. under full load conditions the l6668 switching frequency has been set to 65 khz in order to achieve good efficiency and to limit the switching noise. it's possible to note that the ch3 relevant to the output voltage of the pfc circuit shows the tracking boost function setting at a different pfc output voltage (247 / 348 volts), which is dependent on the mains input voltage as mentioned on the previous page. in figure 17 the drain voltage waveforms and the measurement of the peak voltage at full load and maximum mains input voltage are shown. the maximum voltage peak in this condition is 676 v, which ensures reliable operation of the power mosfet with a good margin against the maximum bv dss . figure 15. EVAL6668-75W flyback stage waveforms @115 v, 60 hz-full load figure 16. EVAL6668-75W flyback stage waveforms @230 v, 50 hz-full load ch1: input mains voltage ch2: input mains current ch3: pfc output voltage ch1: input mains voltage ch2: input mains current ch3: pfc output voltage
functional check an2521 14/33 figure 17. adapter circuit primary side waveforms 265 v, 50 hz 3.2 standby and no-load operation in figure 18 and figure 19 , some no-load waveforms of the ci rcuit are shown. as illustrated, the l6668 works in burst mode to achieve optimal efficiency. the burst mode threshold can be adjusted by setting the divider connected to the skipadj pin (#9). when the voltage at the comp pin falls 50 mv below the voltage on the skipadj pin, the ic is shut down and consumption is reduced. the chip is re-enabled as the voltage on the comp pin exceeds the voltage on the threshold set by pin 9 with its hysteresis. additionally, in order to achieve the best efficiency during light load operation the pfc stage is turned off. in fact, the l6668 pin #14 (pfc_stop) is dedicated to enabling or disabling pfc operation according to the ch1: q7 drain voltage ch2: l6668 vpin #12 (isen) figure 18. eval6668-75 w no-load operation waveforms @90 v, 60 hz figure 19. eval6668-75 w no-load operation waveforms @265 v, 50 hz ch1: q7 drain voltage ch2: l6668 comp (pin #10) ch3: l6668 v cc (pin #5) ch1: q7 drain voltage ch2: l6668 comp (pin #10) ch3: l6668 v cc (pin #5)
an2521 functional check 15/33 output load level. this pin is intended to drive the base of a pnp transistor in systems including a pfc pre-regulator, to stop the pfc controller at light load by cutting its supply. pin #14 (pfc_stop), while normally low, opens if the voltage on the comp pin is lower than 2.2 v, and returns low when the voltage on the comp pin exceeds 2.7 v. whenever the ic is shut down, either latched (dis > 2.2 v, isen > 1.5 v) or not latched (uvlo, skipadj < 0.8), the pin is open as well. in figure 19 , the v cc value is also given, showing that the ic is powered with a good margin with respect to the l6668 turn-off threshold (9.4 v), avoiding any spurious turn-off possibilities that co uld affect the output voltage stability. in ta b l e 3 , the power consumption from the mains during no-load operation is shown. as can be observed, thanks to the l6668 standby functionality the input power constantly remains well below 300 mw. therefore, all mandatory or voluntary regulations currently applicable or that will become effective in the near future can be respected using this chipset. in figure 20 and figure 21 , the transitions from full load to no-load and vice-versa at maximum input voltage have been checked. the maximum input voltage has been chosen for the above illustrations because it is the most critical input voltage for transition. in fact, at no-load, the burst pulses have a lower repetition frequency and the v cc could drop, causing restart cycles of the controller. additionally, there is a wider range variation for the input table 3. input power at no-load vs. mains voltage vin [vrms] input power [w] 90 0.126 115 0.146 (1) 1. compliant to cec, eu-coc, energy star 230 0.268 (1) 265 0.282 figure 20. eval6668-75 w transition full load- to-no load at 265 v, 50 hz figure 21. eval6668-75 w transition no load- to-full load at 265 v, 50 hz ch1: q2 drain voltage ch2: l6668 soft start - pin #11 ch3: output voltage ch4: l6668 v cc (pin #5) ch1: q2 drain voltage ch2: l6668 soft start - pin #11 ch3: output voltage ch4: l6668 v cc (pin #5)
functional check an2521 16/33 voltage to the flyback converter as a result of the pfc turning on or off. as the figures show, both transitions are clean and there is no output voltage, v cc dip or restarting attempt that could affect proper power supply operation. the input power consumption of the board has also been checked at light load conditions, simulating an adapter powering a laptop pc during power-saving operation. the results are shown in ta bl e 4 , 5 and 6 below, where the low load efficiency with standard inputs of 115 v and 230 v is calculated. as visible in ta bl e 4 , 5 and 6 , the input power consumption is always very low and the efficiency remains significantly high even at output power levels where the power supply efficiency normally drops. this is achieved t hanks to the burst mode adjustable threshold of the l6668 skipadj pin and the pfc management by the pfc_stop pin, as previously described. 3.3 over current and short circuit protection an important function of any power supply is its ability to survive instances of output overload or short circuit, avoiding any co nsequent failure. additionally, the power supply must be compliant with safety rules which requi re that the components will not melt or burn- out in fault conditions. it?s comm on to find circuits with good protection capability against load shorts but which do not survive dead shorts such as those of an output electrolytic capacitor or a secondary rectifier, or in cases of transformer saturation. moreover, in cases of a shorted rectifier the equivalent circuit changes and the energy are delivered even during the on time, as in forward mode. in this evaluation board the over-current is managed by u5, a cc/cv controller. inside the ic there is a reference and two or-end operational amplifiers, one dedicated to act as the error amplifier of the voltage loop and the other dedicated to act as the error amplifier of the current loop. if the output current exceeds the programmed value, the current loop error amplifier takes over and, via the optocoupler, table 4. light load efficiency (0.5 w) vin ac [vrms] pout [w] pin [w] efficiency 115 0.52 0.75 (1) 1. compliant to us executive order 13221 ?1w _standby? 68.67% 230 0.52 0.88 (1) 58.52% table 5. light load efficiency (1.2 w) vin ac [vrms] pout [w] p in [w] efficiency 115 1.2 1.55 77.86% 230 1.2 1.71 70.35% table 6. light load efficiency (2.4 w) vin ac [vrms] pout [w] p in [w] efficiency 115 2.41 2.93 82.14% 230 2.4 3.14 76.56%
an2521 functional check 17/33 controls the voltage at the comp pin of the l6668, thus regulating the output current. in case of a dead short, the curr ent cannot be limited effectively by u5 because it will be unpowered. therefore, additional, efficient pr otection circuitry on the primary side will be needed. in this board the voltage at the isen pin of the l6668 is sensed and if it exceeds the v isendis threshold the controller is forced to work in hiccup mode. in this way the controller stops operation and will remain in the off state unt il the voltage across the v cc pin decreases to a level below th e uvlo threshold. it will then attempt to restart, but without success if the secondary short has not been removed. this provides a low frequency hiccup working mode, limiting the current flowing on the secondary side and thus preventing the power supply from ov erheating and failing. figure 22 shows the circuit behavior during short circuit. observe that the l6668 stops switching, the v cc voltage drops until it reaches the uvlo threshold. then the ic decreases its consumption, thus increasing th e duration of the off time, and avoiding high dissipation on the secondary side under short conditions. t he soft start capacitor will also be discharged. at this point, the hv start-up pin recharges the v cc capacitor and, as soon the turn-on threshold is reach ed, the circuit attempts to re start but it will cease operation within a few milliseconds, repeating the sequence just described. the restart attempt will be repeated indefinitely until the short is removed. figure 23 , instead, shows the sequence of operation in short circuit when the short is removed. as the figure illustrates, a new st art-up sequence takes place and the circuit resumes normal operation after a soft-start cycle. thanks to the tsm1014 and the hv current source of the l6668, the fault protection sequences described in figure 22 and figure 23 do not change significantly for any other input voltage, above all not in the input voltage range of the board. the protection described previously works correctly even in cases where the output short is applied during standby or no load operations. the l6668 protects the circuit via the sequences that has been described for the full load operation, and the circuit resumes figure 22. eval6668-75 w short circuit at full load & 230 vac-50 hz figure 23. eval6668-75 w short circuit removal at full load & 230 vac-50 hz ch1: q2 drain voltage ch2: soft start voltage - pin #11 ch3: output voltage ch4: v cc ch1: q2 drain voltage ch2: soft start voltage - pin #11 ch3: output voltage ch4: v cc
functional check an2521 18/33 correct operation when the short is removed. in figure 24 and figure 25 both sequences are captured during 230 vac operation but they do not change significantly over the input mains range. 3.4 overvoltage and op en loop protection the EVAL6668-75W board implements two different open loop protections: one for the pfc and another for the flyback stage. the pfc controller l6563 is equipped with an ovp, monitoring the current flowing through the compensation network and entering the error amplifier (pin comp, #2). when this current reaches about 18 a the output voltage of the multiplier is forced to decrease, thus reducing the energy drawn from the mains. if the current exceeds 20 a, the ovp is triggered (dynamic ovp), and the external power transistor is switched off until the current falls below approximately 5 a. however, if the overvoltage persists (e.g. if the load is completely disconnected), the error amplifier will eventually saturate low, triggering an internal comparator (static ovp) which will keep the external power switch turned off until the output voltage returns to a point near the regulated value. the ovp function described above is capable of handling "normal" overvoltage conditions, i.e. those resulting from an abrupt load/line change or occurring at start-up. it cannot handle the overvoltage generated, for instance, when the upper resistor of the output divider fails open. the voltage loop can no longer read the information on the output voltage and will force the pfc pre-regulator to work at maximum on time, causing the output voltage to rise uncontrollably. a pin on the l6563 (pfc_ok, #7) has been provided for additional monitoring of the output voltage with a separate resistor divider (r3, r5, r11 high, r19 low, see figure 1. and 2 ). this divider is selected so that the voltage at the pin reaches 2.5 v if the output voltage figure 24. eval6668-75 w short circuit at no- load & 230 vac-50 hz figure 25. eval6668-75 w short circuit removal at no-load & 230 vac-50 hz ch1: q2 drain voltage ch2: soft start voltage - pin #11 ch3: output voltage ch4: v cc ch1: q2 drain voltage ch2: soft start voltage - pin #11 ch3: output voltage ch4: v cc
an2521 functional check 19/33 exceeds a preset value, usually larger than the maximum vo that can be expected, including also overshoots due to worst-case load/line transients. in this case, vo = 400 v, vox = 460 v. select: r3 + r5 + r11 = 6.6 m ? . three resistors in series have been chosen according to their voltage rating. thus: r19 = 6.6 m ? 2.5 / (460-2.5) = 36 k ? . when this function is triggered, the gate drive activity is immediately stopped, the device is shut down, its quiescent consumption is reduced below 250 a and the condition is latched as long as the supply voltage of the ic is above the uvlo threshold. at the same time the pin pwm_latch (pin #8) is asserted high. the pwm_latch is an open source output capable of delivering 3.7 v minimum with a 0.5 ma load, intended for tripping a latched shutdown function of the pwm controller ic in the cascaded dc-dc converter, so that the entire unit is latched off. to restart the system it is necessary to recycle the input power, so that the v cc voltages of both the l6563 and the pwm controller go below their respective uvlo thresholds. the pfc_ok pin doubles its func tion as a not-latched ic disa ble: a voltage below 0.2 v will shut down the ic, reducing its consumption below 1 ma. in this case both pwm_stop and pwm_latch keep their high impedance status. to restart the ic simply let the voltage at the pin go above 0.26 v. note that this function offers complete protection against not only feedback loop failures or erroneous settings, but also against a failure of the protection itself. if a resistor in the pfc_ok divider fails short or op en, or the pfc_ok (#7) pin is floating, it will result in the shutting down of the l6563 and stopping of controller operation of the flyback stage. figure 26. EVAL6668-75W open loop at 115 vac-60 hz - full load an open loop event is captured in figure 26 . note the protection intervention stopping the operation of the l6563 and the activation of the pwm_latch pin that is connected to the l6668 pin #7 (dis). this function of the l6668 is a latched device shutdown. internally the pin connects a comparator which shuts the ic down and brings its consumption to a value just higher than before start-up, when the voltage on the pin exceeds 2.2 v. the information is latched and it is necessary to recycle the input power to restart the ic. the latch is removed as the voltage on the v cc pin goes below the uvlo threshold.
EVAL6668-75W: thermal map an2521 20/33 the flyback stage is also protected against open loop conditions that lead to loss of control of the output voltage. a divider connected to the aux iliary winding of the transformer is also connected to the l6668 pin #7 (dis) and, in case of excessively high output voltage resulting from loop failure, provides for the triggering of the internal comparator connected to that pin. in this case oper ation of the l6563 will cease bec ause the l6668 will stop the pfc stage operation via the pfc_stop pin. the v cc powering both the ics will be maintained by the hv start-up generator of the l6668. to restart the operation, it will be necessary to unplug and re-plug the mains, to unlatch the l6668. 4 EVAL6668-75W: thermal map 4.1 thermal protection the EVAL6668-75W is also equipped with thermal protection of the flyback's power mosfet (q5). its temperature is sensed using the ntc thermistor r58 connected to the l6668 pin #7 (dis). if the temperature of the heat sink rises above the maximum allowed level (80 - 85 c), the threshold of the inte rnal comparator will be exceeded and the l6668 latched as in the case of ope n loop. to restart the operat ion of the circuit, it will be necessary to unplug and re-plug the mains. 4.2 thermal map in order to check the reliab ility of the design, thermal ma pping has been performed using an infrared camera. in figure 27 and 28 , the thermal measurements on the key components at nominal input voltage are shown. the correlation between the measurement points and components for both thermal maps is indicated in ta b l e 7 below. the ambient temperature during both measurements was 27 c. all other components on the board work within the temperature limits, ensuring reliable long-term operation of the power supply. figure 27. thermal map at 115 vac-60 hz - full load
an2521 EVAL6668-75W: thermal map 21/33 figure 28. thermal map at 230 vac-50 hz - full load table 7. measured temperature table @115 vac and 230 vac - full load point component temperature @115 vac temperature @230 vac a d2 59.6 c 52.9 c b q2 59.9 c 54.0 c c d4 101 c 100 c d q5 75.8 c 67.2 c e t1 - winding 76.1 c 77.7 c f t1 ? core 74.9 c 76.3 c g d7 77.4 c 75.7 c h r1 (ntc) 100 c 80.5 c
conducted emission pre-compliance test an2521 22/33 5 conducted emission pre-compliance test the following figures are the peak measurements of the conducted noise emissions at full load and nominal mains voltages. the limits shown on the diagrams are those of en55022 class-b, which are most popular requirements for domestic equipment and imposes less stringent limits compared to the class-a, which is dedicated to it technology equipment. as visible in the diagrams, in all test conditions there is a good margin for the measurements with respect to the limits. figure 29. ce peak measure at 100 vac and full load figure 30. ce peak measure at 230 vac and full load
an2521 bill of material 23/33 6 bill of material table 8. EVAL6668-75W evaluation board: bill of material des. part type/part value description supplier c1 2n2 y1 safety cap. murata c10 res. not used c11 res. not used c12 1000 f-25v zl aluminium elcap - zl series - 105 c rubycon c13 100 f-25v yxf aluminium elcap - yxf series - 105 c rubycon c14 220nf 50 v cercap - general purpose avx c15 1 f 25 v cercap - general purpose avx c16 1000 f-25v zl aluminium elcap - zl series - 105 c rubycon c17 100n 50 v cercap - general purpose avx c19 2n2 50 v cercap - general purpose avx c2 2n2 y1 safety cap. murata c20 10n 50 v cercap - general purpose avx c21 470n 25 v cercap - general purpose avx c22 22-25 v aluminium elcap - yxf series - 105 c rubycon c23 res. not used c24 2n2 - y1 - de1e3kx222m y1 safety cap. murata c25 220pf 50 v cercap - general purpose avx c26 22n 50 v cercap - general purpose avx c27 47 f-50 v aluminium elcap - yxf series - 105 c rubycon c28 res. not used c29 res. not used c3 470n-x2 x2 film capacitor - r46-i 3470--m1- arcotronics c30 2n2-5% 50 v - 5% - c0g - cercap avx c31 res. not used c32 100n 50 v cercap - general purpose avx c33 22 f-50 v aluminium elcap - yxf series - 105 c rubycon c34 100pf 50 v cercap - general purpose avx c35 270n 25 v cercap - general purpose avx c36 100n 50 v cercap - general purpose avx c37 82n 50 v cercap - general purpose avx c38 470pf 50 v cercap - general purpose avx
bill of material an2521 24/33 c39 4n7 50 v cercap - general purpose avx c4 470n-x2 x2 film capacitor - r46-i 3470--m1- arcotronics c40 100n 50 v cercap - general purpose avx c41 10n 50 v cercap - general purpose avx c42 10 f-63 v aluminium elcap - sr series - 85 c rubycon c43 2n2 50 v cercap - general purpose avx c44 100n 50 v cercap - general purpose avx c5 470n-400 v b32653a4474j - polyprop. film cap epcos c6 100 f-450 v aluminium elcap - lls series - 85 c nichicon c7 2n2 - y1 - de1e3kx222m y1 safety cap. murata c8 1n0-200 v 200 v cercap - general purpose avx c9 100n 50 v cercap - general purpose avx d1 1n4005 general purpose rectifier vishay d10 ll4148 fast switching diode vishay d11 bav103 fast switching diode vishay d12 ll4148 fast switching diode vishay d13 ll4148 fast switching diode vishay d14 ll4148 fast switching diode vishay d15 res. not used d2 gbu4j single phase bridge rectifier vishay d3 stth2l06 ultrafast high voltage rectifier stmicroelectronics d4 1.5ke250a transil stmicroelectronics d5 bzv55-b30 zener diode vishay d6 res. not used d7 stps20h100cfp high voltage power schottky rectifier stmicroelectronics d8 stth108a high voltage ultrafas t rectifier stmicroelectronics d9 bzv55-c8v2 zener diode vishay f1 fuse 4 a fuse t4a - time delay wichmann j1 mkds 1,5/ 3-5,08 pcb term. block, screw conn., pitch 5mm - 3 w. phoenix contact j2 mkds 1,5/ 2-5,08 pcb term. block, screw conn., pitch 5mm - 2 w. phoenix contact jp5 jumper tinned copper wire jumper jp7 res. tinned copper wire jumper - not used jp10 jumper tinned copper wire jumper jp11 jumper tinned copper wire jumper table 8. EVAL6668-75W evaluation board: bill of material (continued) des. part type/part value description supplier
an2521 bill of material 25/33 jp12 jumper tinned copper wire jumper jp13 jumper tinned copper wire jumper jp14 jumper tinned copper wire jumper l1 hf2826-253y1r2-t01 25 mh-1 .2 a input emi filter tdk l2 srw25cq-t03h112 400 h pfc inductor tdk l3 tsl0706 - 1r5-4r3 1 5 - radial inductor tdk q1 bc857c pnp small signal bjt zetex q2 stp9nk50zfp n-channel powe r mosfet stmicroelectronics q3 res. not used q4 res. not used q5 stp10nk80zfp n-channel powe r mosfet stmicroelectronics q6 bc857c pnp small signal bjt zetex q7 res. not used q8 bc847c npn small signal bjt zetex r1 ntc 10r-s236 ntc resistor 10r - p/n b57236s0100m000 epcos r10 res. not used r11 2m2 - 1% smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r12 3m3 smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r13 res. not used r14 3r9 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r15 res. not used r16 10 k ? smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r17 62 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r18 51 k ? smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r19 36 k ? smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r101 0r0 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r102 0r0 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r103 0r0 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r104 0r0 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r105 0r0 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r2 1m0-1% smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r20 20 k ? smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r21 res. not used r22 r015 - 1 w smd film res. 1 w - 2512 msr1 meggit r23 27r smd std film res. - 1/4 w - 5% - 250 ppm/c bc components table 8. EVAL6668-75W evaluation board: bill of material (continued) des. part type/part value description supplier
bill of material an2521 26/33 r24 100 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r25 470r sfr25 axial stand. film res. - 0.4 w - 5% - 250 ppm/c bc components r26 120 k ? smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r27 0r33 sfr25 axial stand. film res. - 0.4 w - 5% - 250 ppm/c bc components r28 2k2 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r29 res. not used r3 2m2 - 1% smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r30 22 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r31 4k7 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r32 res. not used r33 10 k ? smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r34 270 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r35 2r7 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r36 1k8 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r37 10 k ? - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r38 res. not used r39 56 k ? - 1% smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r4 68 k ? smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r40 res. not used r41 10 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r42 8k2 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r43 4r7 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r44 47 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r45 2k2 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r46 47r smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r47 100 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r48 4k7 - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r49 24 k ? - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r5 2m2 - 1% smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r50 1k0 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r51 2k2 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r52 0r39 sfr25 axial std film res. - 0.4 w - 5% - 250 ppm/c bc components r53 0r39 sfr25 axial stand. film res. - 0.4 w - 5% - 250 ppm/c bc components r54 47 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r55 22r smd std film res. - 1/8 w - 5% - 250 ppm/c bc components table 8. EVAL6668-75W evaluation board: bill of material (continued) des. part type/part value description supplier
an2521 bill of material 27/33 r56 4k7 - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r57 100r sfr25 axial stand. film res. - 0.4 w - 5% - 250 ppm/c bc components r58 m57703 - 10 k ? 10 k thermistor - b57703m0103g040 epcos r59 24 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r6 1m0 - 1% smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r60 56 k ? smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r61 33 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r62 3k3 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r63 0r0 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r64 43 k ? - 1% sfr25 axial stand. film res. - 0.4 w - 1% - 100 ppm/c bc components r65 22 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r66 3r9 smd std film res. - 1/4 w - 5% - 250 ppm/c bc components r67 6k2 - 1% smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r68 120 k ? - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r69 1k0 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r7 3m3 smd std film res. - 1/4 w - 1% - 100 ppm/c bc components r71 res. not used r72 0r0 smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r73 62 k ? smd std film res. - 1/8 w - 5% - 250 ppm/c bc components r8 75 k ? - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components r9 75 k ? - 1% smd std film res. - 1/8 w - 1% - 100 ppm/c bc components t1 srw32ec-t01h114 power transformer tdk u1 l6563 transition mode pfc controller stmicroelectronics u2 l6668 smart primary controller stmicroelectronics u3 sfh617a-4 optocoupler infineon u4 res. not used u5 tsm1014 low consumption cc/cv controller stmicroelectronics hs1 heat sink for d2&q2 hs2 heat sink for q5 hs3 heat sink for d7 table 8. EVAL6668-75W evaluation board: bill of material (continued) des. part type/part value description supplier
pfc coil specification an2521 28/33 7 pfc coil specification 7.1 general description and characteristics application type: consumer, home appliance inductor type: open coil former: vertical type, 5+3 pins max. temp. rise: 45 c max. operating ambient temp.: 60 c mains insulation: n.a. unit finishing: varnished 7.2 electrical characteristics converter topology: boost, transition mode core type: cq25 - pc47 minimum operating frequency: 20 khz typical operating frequency: 400 h 10% @1 khz - 0.25 v (see note: 1 ) peak primary current: 3.5 a pk rms primary current: 1.2 a rms note: 1 measured between pins #5 and #6 7.3 electrical schematic and winding characteristics figure 31. electrical diagram table 9. winding characteristics pins winding rms current number of turns wire type 8 - 3 aux (1) 1. aux winding is wound on coil former before primary wi nding. to be insulate with a layer of polyester tape. 0.05 a rms 5 spaced ? 0.28 mm 5 - 6 primary (2) 2. primary winding external insulati on: 2 layers of polyester tape 1.2 a rms 50 multi stranded #10 x ? 0.20 mm 5 6 prim. aux 8 3
an2521 pfc coil specification 29/33 7.4 mechanical aspect and pin numbering maximum height from pcb: 20 mm coil former type: vertical, 5+3 pins pins #1, 2, 4, 7 have been removed external copper shield: not insulated, wound around the ferrite core and including the coil former. height is 7 mm. connected to pin #3 by a solid wire. figure 32. mechanical aspect and pin numbering of pfc coil a: 27.0 max mm b1: 3.0 0.3 mm b2: 5.0 0.3 mm c: 3.3 0.3 mm d: 19.0 max mm e: 21.0 0.5 mm f: 23.7 0.5 mm 25cq-txx tdk ? ???? 6 5 15 1 5 6 8 15 6 8 a d c f e b1 b1b1 b1 b2 b2 x8 7'. 1. external copper sheet (0.025x7 mm) 2. mylar tape - 1 turn
transformer specification an2521 30/33 8 transformer specification 8.1 general description and characteristics application type: consumer, home appliance transformer type: open winding type: layer coil former: horizontal type, 9+9 pins max. temp. rise: 45 c max. operating ambient temp.: 60 c mains insulation: acc. with en60950 unit finishing: varnishing 8.2 electrical characteristics converter topology: flyback, ccm/dcm mode core type: eer34 - pc47 min. operating frequency: - typical operating freq: 60 khz primary inductance: 550 h 10% @1 khz - 0.25 v (see note 1 ) leakage inductance: 17 h max @ 100 khz - 0.25 v (see note 1 - note 2 ) max. peak primary current: 2.65 a pk rms primary current: 0.78 a rms note: 1 measured between pins 1-3 2 measured between pins 1-3 with all secondary windings shorted 8.3 electrical diagram an d winding characteristics figure 33. electrical diagram 8 9 aux 10-11 15-16 +12v 5 2 prim. a 6 3 prim. b
an2521 transformer specification 31/33 note: all terminal wires must be insulated by tube figure 34. winding position on coil former note: primaries a & b are in parallel 8.4 mechanical aspect and pin numbering maximum height from pcb: 30 mm coil former type: horizontal, 9+9 pins (pin 2 removed) pin distance: 4 mm row distance: 35 mm external copper shield: not insulated, wound around the ferrite core and including the coil former. height is 12 mm. table 10. winding characteristics pin winding o/p rms current number of turns number of layers wire type 5 - 6 aux 0.05 a rms 7 spaced 1 g2 ? 0.23 mm 3 - 1 primary - a 0.39 a rms 60 2 g2 ? 2 x 0.23 mm 8 - 10 19 v 5.2 a rms 81 multistrand g2 - 4 x 0.64 mm 4 - 2 primary - b 0.39 a rms 60 2 g2- 2 x 0.23 mm polyester tape - 2 layers polyester tape - 2 layers polyester tape - 2 layers polyester tape - 1 layers coil former 6.2 6.2 primary - b 19v primary - a aux barrier tape
revision history an2521 32/33 figure 35. mechanical aspect and pin numbering of flyback transformer a: 38.0 max mm b: 4.0 0.3 mm c: 3.5 0.5 mm d: 26.5 max mm e: 40.0 max mm f: 35.0 0.5 mm 9 revision history 1. external copper sheet (0.025x12 mm) 2. mylar tape - 1 t table 11. document revision history date revision changes 24-oct-2007 1 initial release
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