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june 2010 doc id 16181 rev 2 1/27 AN3040 application note steval-ilb008v1 4 x 18 w/t8 ballast driven by l6585de introduction this application note describes a demonstration board able to drive a 4 x 18 w linear t8 fluorescent tubes. the ballast is controlled by the new l6585de ic that integrates the pfc and half-bridge control circuits, relevant drivers, and the circuitry that manages all the operating phases (preheating, ignition and run mode) of the lamp. protections against failures such as lamp disconnection, anti-capacitive mode and pfc overvoltage are guaranteed and obtained with a minimum number of external components. in addition to the description of the circuit and design criteria, this document provides a short overview of the ballast performances. fluorescent lamps are driven more and more by electronic ballasts rather than by electromagnetic ballasts, primarily because fluorescent lamps can produce around 20% more light for the same input power when driven above 20 khz instead of 50/60 hz. operation at this frequency also eliminates both light flickering (the response time of the discharge is too slow for the lamp to have a chance to extinguish during each cycle) and audible noise. electronic ballasts consume less power and therefore dissipate less heat than electromagnetic ballasts. the energy saved can be estimated in the range of 20-25% for a given lamp power. finally, the electronic solution allows better control of the filament current and lamp voltage during preheating with the unquestionable benefit of increasing the average lamp life. figure 1. 4 x 18 w t8 ballast demonstration board !-v www.st.com
contents AN3040 2/27 doc id 16181 rev 2 contents 1 basis of half-bridge inverter t opology . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 main characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 ballast design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 l6585de pin-by-pin biasing circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 pfc power section design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2.1 input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2.2 output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2.3 boost inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2.4 power mosfet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2.5 boost diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.3 design of the half-bridge inverter and choice of preheating inductor . . . . 14 4 experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.1 start sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.2 protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.3 conducted emissions test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.4 guidelines for connecting the four lamps to the ballast . . . . . . . . . . . . . . 20 5 automatic restart circuit fo r lamp replacement . . . . . . . . . . . . . . . . . . 21 6 bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 7 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
AN3040 list of figures doc id 16181 rev 2 3/27 list of figures figure 1. 4 x 18 w t8 ballast demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 figure 2. electrical architecture used for four-lamp electronic ballasts . . . . . . . . . . . . . . . . . . . . . . . . 4 figure 3. electrical schematic 4 x 18 w t8 - main wide range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 figure 4. eol circuit for first-series lamp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 figure 5. l6585de startup sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 6. one lamp ignition phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 7. lamp voltage and current in run mode condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 8. run mode, rectifying effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 9. ignition phase with broken lamps: case 1 (lamp 1 works, lamp 2 is broken, lamp 3 is broken, lamp 4 works) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 figure 10. ignition phase with broken lamps: case 2 (lamp 1 is broken, lamp 2 works, lamp 3 is broken, lamp 4 works) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 figure 11. conducted emissions at 110 vac 50 hz - line 1 peak detector . . . . . . . . . . . . . . . . . . . . . 19 figure 12. conducted emissions at 110 vac 50 hz - line 2 peak detector . . . . . . . . . . . . . . . . . . . . . 19 figure 13. conducted emissions at 230 vac 50 hz - line 1 peak detector . . . . . . . . . . . . . . . . . . . . . 19 figure 14. conducted emissions at 230 vac 50 hz - line 2 peak detector . . . . . . . . . . . . . . . . . . . . . 20 figure 15. connecting four lamps to the ballast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 figure 16. automatic restart circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
basis of half-bridge inverter topology AN3040 4/27 doc id 16181 rev 2 1 basis of half-bridge inverter topology the half-bridge inverter operates in zero voltage switching (zvs) resonant mode to reduce the switching losses and the electromagnetic interference generated by the output wiring and the lamp. voltage-fed, series-resonant, half-bridge inverters are currently used for compact fluorescent lamp (cfl) ballasts and for many european tube lamp (tl) ballasts. for this circuit, we have chosen a lamp-to- ground configuration with current preheating and have implemented two parallel resonant circuits that each supply two lamps in series, as shown in figure 2 . figure 2. electrical architecture used for four-lamp electronic ballasts !-v / 5( & 5( & %or & %or / 5( & 5(
AN3040 main characteristic doc id 16181 rev 2 5/27 2 main characteristic the electrical specifications of the lamp ballast are shown in ta bl e 1 . table 1. input and output parameter input parameters v in input voltage range 85 to 265 v rms f line line frequency 50/60 hz tube lamp number 4 ty p e t 8 power 18 w expected output parameters pf power factor 0.9 thd% total harmonic distortion 10 % efficiency 90
main characteristic AN3040 6/27 doc id 16181 rev 2 figure 3. electrical schematic 4 x 18 w t8 - main wide range !-v /$03 7 /dps: 5 0 5 0 5 & s)9 /suhk p+$upv 5 /$03 7 /dps: 5 0 5) ,19 *1' 2xw 9&& /6' &75 (2/3 (2/5 +%&6 +6' %rrw 0xow &rps 2vf (2, 7&+ 3)* =&' 3)&6 8 /'( 5 n2kp & q)9 5 n & q)9 5 n 5 n2kp 5 2kp 5 n2kp 5 n2kp / p+ /3)& p+ & q) & q)9 / p+ ' %$7= 5 n2kp ' %$7= & q)9$&< 5 n 5 4 67'101 & q)9 & q )9; /$03 7/dp s: 5 n - &21 5 2kp 5 .2kp & q )9 & x) & s)9 & x )9 ' 9: 5 rkp: 5 2kp 5 nn: & q) 5 n2kp 5 n2kp 5 n2kp 5 n: & &$313 ' 9: ' 1 ' 9 5 n2kp 4 67'1. ) $ 4 67'1. /suhk p+$upv & q) /f [p+$ ' *)0 ' 677+/ & q) & x)9 /$03 7 /dps: 5 02kp 5 02kp ' *)0 & q) & q)9; ' *)0 ' *)0 5 n2kp 5 rkp: & q ) 5 n2kp 5 2kp ' 1 5 & q)9 ' 9: & q)9 ' 9: & s )9 5 0
AN3040 ballast design doc id 16181 rev 2 7/27 3 ballast design this sections describes the ma in components of the circuit. 3.1 l6585de pin-by-pin biasing circuitry designed in high-voltage bcd offline technology, the l6585de embeds a pfc controller, a half-bridge controller, the relevant drivers and the logic necessary to build an electronic ballast. pin1 osc is one of the two oscillator inputs . the value of the capacitor connected to ground defines the half-bridge switching frequency in each operating state. c 5 is set to 1 nf. pin2 rf: the choice of component and osc illator capacitance defin es the half-bridge switching frequency in each operating state. a resistor r 14 connected to ground sets the run frequency, while during the preheating phase the switching frequency is set by the parallel of the above resistance with the r 13 resistor connected between the rf and eoi pins (the eoi pin is pulled to ground during preheating). with the following frequencies and ignition time: r 14 can be calculated with the following formula. equation 1 the value of r 13 is therefore given by: equation 2 pin3 eoi is a multi-function pin. during preheating, the pin is internally shorted to ground by the logic, so the resistor (rpre//rrun) connected between the rf pin and ground sets the preheating switching frequency. during ignition it goes into a high impedance state: the ignition time is the time necessary for the pin voltage to - exponentially - rise from zero to 1.9 v. the growth is steered by the c 6 *r 13 time constant; since the value of r 13 has already been calculated and t ign at the start is fixed, c 6 is calculated with the following formula. equation 3 for this circuit, c 6 has been set to 320 nf. khz 40 f run = = = () 581 . 0 5 c 33 . 1 1 e ? = () 872 . 0 5 3 c 10 6 . 499 k ? = = ? ? ? ? ? ? ? ? = k 33 f k r e / 1 run 14 = ? ? ? ? ? ? ? ? ? = k 47 r f k r // r 13 e / 1 pre 14 13 nf 319 r 3 t c 13 ign 6 = ? =
ballast design AN3040 8/27 doc id 16181 rev 2 pin4 tch is the time counter and is activa ted during the preheating phase as well as after a protection is triggered (hbcs crossing during ignition run mode, window comparator at eol). to achieve this, an r 15 c 7 parallel network is connected between this pin and ground. with a protection time t tch,reduced fixed at 0.27 seconds (needed for the startup sequence with old or damaged lamps), c 7 can then be calculated. equation 4 with t pre set to 1 second and considering the internal current generator i ch = 31 a, r 15 can be calculated. equation 5 pin5 eolp is a 2 v reference and allows programming the window comparator of pin6 (eol) according to the values defined in ta bl e 4 in the l6585de datasheet. working in a lamp-to-ground configuration, a fixed reference mode has been selected, and for a window voltage amplitude of 240 mv, r 16 has been set to 75 k . pin6 eol is the input of the window comparator. concerning this comparator, the fixed reference configuration requires two zener diod es to shift the mean value of the lamp voltage to 2.5 v. the values of the two ze ner diodes relate to the symmetry of the protection intervention, and the best symmetr y is obtained by choosing two values whose difference is equal to twice the reference voltage. referring to the first series lamp ( figure 3 ): equation 6 if we consider that v fd17 = v fd16 = 0.7 v and take into account that w/2 = 0.240 v, the maximum/minimum voltage on the low resistan ce of the voltage divider of the lamp is . with r 67 equaling 1.8 m , considering the current capabilit y of eol and fixing the maximum deviation voltage lamp , the value of r 60 can be calculated as 1.5 m . f 1 c 10 26974 . 0 c t 7 6 7 reduced , tch = ? ? ? ? ? = ? ? ? = k 750 k 755 5 . 1 63 . 4 ln c 63 . 4 i c t r 7 ch 7 pre 15 2 w v v 5 . 2 v 17 fd 16 zd max k + + + = ( ) 2 w v v 5 . 2 v 16 fd 17 zd min k ? + ? = ? ? = min k max k v v v 10 v , v 1 . 5 v v v 5 . 2 2 16 zd 17 zd 16 zd 17 zd = = ? ? = ? v k 8.2v = v lamp 18v =
AN3040 ballast design doc id 16181 rev 2 9/27 figure 4. eol circuit for first-series lamp the same design procedure can be used for the eol circuit of the second series lamp. pin7 ctr is a multi-function pin (pfc overvo ltage, feedback disconnection, reference for eol in case of tracking reads), connected through a resistive divider to the pfc output bus. by establishing a maximum pf c overvoltage (pfc output overshoot, for example, at startup) v ovpbuspfc of 480 v and considering that the corresponding threshold on the ctr pin (v thrctr) must be 3.4 v, r 7 +r 12 can be calculated as 1.82 m and r 19 as 13 k . pin8 mult: first, the maximum peak value for v mult , v multmax is selected. this value, which is reached at the maximum mains voltage, should be 3 v (linearity limit) or nearly so in wide-range mains and less in case of single mains. the pfc sense resistor selected is r s = r 22 = 0.150 and is described in the section on pin12. considering that the maximum slope of the multiplier (maxsl ope) is 0.75, it is possible to calculate the maximum peak value occurring at the maximum mains voltag e and the multiplier divider . equation 7 83 . 1 v v slope max r pf v p 2 2 v v slope max r i v min ac max ac 22 min in out min ac max ac 22 lpk max mult = ? ? ? ? ? ? = ? ? = () 3 max ac max mult 9 5 17 17 10 89 . 4 265 2 83 . 1 v 2 v r r r r ? ? = ? = ? = + + =
ballast design AN3040 10/27 doc id 16181 rev 2 supposing there is a 240 a current flowing into the divider, the value of the lower resistor r 17 can be calculated, and then the value of the upper resistance r 5 +r 9 . equation 8 the voltage on the multiplier pin with the selected component values is recalculated at a minimum line voltage of 0.59 v and at maximum line voltage of 1.85 v. as a result, the multiplier operates correctly within its linear region. pin9 comp is the output of the e/a and also one of the two inputs of the multiplier. the feedback compensation network, placed between this pin and inv (10), is a capacitor c 2 calculated as follows (considering that r 6 +r 11 is the upper resistance of voltage divider between the pfc bus and the comp pin). equation 9 c 2 has been set to a commercial value of 470//100 nf. pin10 inv: to implement the voltage control loop, a resistive divider ( figure 4 ) must be connected between the regulated output voltage (v buspfc = 420 v) of the boost and the pin. the internal reference on the non-in verting input of the e/a is 2.5 v so r 6 and r 11 ( figure 4 ) can then be selected fixing r 18 to 18 k . equation 10 pin11 zcd is the input to the zero current detector circuit. the zcd pin is connected to the auxiliary winding of the boost inductor throug h a limiting resistor r 10 . the zcd circuit is negative-going, edge-triggered: wh en the voltage on the pin falls below 0.7 v, the pwm latch is set and the mosfet is tur ned on. however, the circuit must first be armed: prior to falling below 0.7 v, the vo ltage on pin 11 must experience a positive- going, edge-exceeding 1.4 v (due to the mosfet switching off). the maximum main- to-auxiliary winding turn ratio (m) has to en sure that the voltage delivered to the pin during the mosfet's off time is sufficient to arm the zcd circuit. equation 11 m has been set to 10. = + ? = ? ? = + = ? = = m 5 . 1 r r m 52 . 1 r 1 r r k 5 . 7 r k 79 . 7 a 240 v r 9 5 17 9 5 17 max mult 17 () nf 530 r r 2 10 c 11 6 2 = + ? ? = 1 5 . 2 v r r r buspfc 18 11 6 ? = + = + m 3 r r 11 6 10 . 33 4 . 1 v 2 v m (max) inrms buspfc = ? ?
AN3040 ballast design doc id 16181 rev 2 11/27 considering the upper and lower clamp volta ges of the zcd pin and its minimum sink current capability acco rding to the maximum and minimu m voltages of the pfc bus, r 10 has been calculated and set to 68 k . pin12 pfcs is the inverting input of the current sense comparator. as the voltage across the sense resistor (proportional to the instantaneous inductor current) crosses the threshold set by the multiplier output, the power mosfet is turned off. equation 12 determines the pfc sense resistor. equation 12 r 22 has been set to 150 m with a power rating of 1 w. pin13 pfg: to drive the external mosfet correctly, r 21 has been set to 100 . pin 14 hbcs: assuming that during each lamp?s ignition phase there is a maximum current i ignmax of 1.9 a and an hbcs threshold during the ignition phase v hbcs-ign of 1.6 v, we can calculate that r sensehb = r 31 . equation 13 r 31 has been set to 0.47 with a power rating of 1 w. pin 15 gnd: device ground. pin 16 lsd: to drive the external half-bridge low-side mosfet correctly, the resistor r 23 has been set to 43 . pin 17 vcc: this pin is externally connected to the startup circuit (by means of r 34 , r 35 , r 36 , r 37 , r 40 and r 41 ) and to the self-supply circuit made of a charge pump composed by the net c 16 , c 17 , c 18 , d 8 , d 9 and r 29 . pin 18 out: floating reference of the high-sid e driver. this pin is connected close to the source of the high-side power mosfet. pin 19 hsd: to drive the external half-bridge low-side mosfet correctly, the resistor r 20 has been set to 43 . pin 20 boot: for the high-side section c 13 has been set to 100 nf. a 68 . 2 pf v p 2 2 i min in outtot max l = ? ? ? = r 22 v csmin i lmax ------------------- 1 2.68 ----------- 0.37 r 22 150m = ? = = < = = ? 42 . 0 i v r tot max ign ign hbcs 31
ballast design AN3040 12/27 doc id 16181 rev 2 3.2 pfc power section design 3.2.1 input capacitor the input high-frequency filter capacitor has to attenuate the switching noise due to the high frequency inductor cu rrent ripple. the wors t conditions will occur on the peak of the minimum rated input voltage (v inmin = 85 v). the following values have been established. the coefficient of the maximum high -frequency voltage ripple r = 0.05. total system efficiency is possible. taking into account a minimum half-bridge switching frequency (f swmin ) of 39 khz and a total output power (p outtot ) equal to 4*18 = 72 w, the input capacitor c 4 can be determined by the following equation. equation 14 to obtain a good margin from f swmin , c 4 has been set to 680 nf. 3.2.2 output capacitor the selection of the output bulk capacitor c 1 depends on the dc output voltage, the admitted overvoltage, the output power and th e desired voltage ripple. with the following values: pfc output voltage v buspfc = 420 v. the coefficient of the low frequency (twice the mains frequency (f main) = 50 hz) voltage ripple r 1 = 0.05. the bulk capacitor can be calculated as: equation 15 to obtain the smallest possible ripple and good reliability, a co mmercial capacitor c 1 of 33 f, 450 v has been used. 3.2.3 boost inductor the inductance l pfc is usually determined so that the minimum switching frequency (f min pfc ) is greater than the maximum frequency of the internal starter to ensure correct tm operation. considering the minimum su ggested value for the pfc section (f min pfc ) is 20 khz and that this last can occur at either the maximum v inrmsmax = 265 v or the minimum v inrmsmin = 85 v mains voltage, the inductor value is defined by: equation 16 nf 904 r v f 2 v p c min in min sw min in outtot 4 = ? ? ? ? ? = f 13 r v f 2 2 v p c 1 buspfc main buspfc outtot 1 = ? ? ? = ( ) buspfc out pfc min inrms buspfc 2 inrms pfc v p f 2 v 2 v v l ? ? ? ? ? ? =
AN3040 ballast design doc id 16181 rev 2 13/27 to margin from f min pfc we have set f pfc to 38 khz. in this condition, the lower value for the inductor is determined by v inrms = v inrmsmin and the result l pfc = 0.8 mh with (as stated in the pfcs pin description) a minimum i lmax of 3 a and a maximum i lmax of 5 a (using the inductor 1646-0004 manufactured by magnetica).
ballast design AN3040 14/27 doc id 16181 rev 2 3.2.4 power mosfet the choice of mosfet re lates mainly to its r ds(on) , which depends on the output power and its breakdown voltage, the latter being fixed by the output voltage v buspfc =420 v only, plus the overvoltage v ovppfc = 60 v allowed, and a safety margin. the mosfet's power dissipation depends on the conduction and switching losses. assuming maximum total power losses p lossesadm = 1%, p outtot = 0.7 w, it easy to verify that with the second-generation mdmesh tm v power mosfet stb12nm50n, the estimated total mosfet power losses p lossesest are about = 0.5 w (worst case) and that this was the correct choice. 3.2.5 boost diode the boost freewheeling diode is a fast recovery one. the breakdown voltage is fixed with the same criterion as the mosfet. the value of its dc and rms current, needed to choose the current rating of the diode, are reported. equation 17 since the pfc works in transition mode, we have used the turbo 2 ultrafast high-voltage rectifier stth1l06. 3.3 design of the half-bridge in verter and choice of preheating inductor according to the criteria described in an993 chapter 5 (design tips) with regard to the design of the resonant circuit, the following values have been selected. we have used the inductor 1646-0005 manufactured by magnetica. a supermesh3 power mosfet std7n52k3 has been inserted in the half-bridge section to reduce the power losses. for the preheating inductor, we have selected a common mode choke-type inductor with the following features: l preh1 = l preh2 = 10 mh/250 v/1.4 a. a 171 . 0 v p i buspfc outtot dc 2 d = = a 53 . 0 v v 9 2 4 i 2 2 i buspfc inrmsmin inrmsmax rms 2 d = ? ? ? = l res l 1 l 2 2.2 mh = = = c res c 9 c 14 4.7nf 1600 v , = = = c block c 12 c 15 100 nf 400 v , = = =
AN3040 experimental results doc id 16181 rev 2 15/27 4 experimental results the schematic of the tested board is shown in figure 3 . the board has been tested for efficiency, power factor, total harmonic distortion and thermal behavior for the input voltage range. ta bl e 2 and ta b l e 3 show the results obtained for a 45-minute test. all the results are very good. efficiency is ap proximately 85%, the power factor corrector is constantly 0.9 and thd is lower than 10%. with regard to the thermal behavior, it is easy to deduct from ta b l e 3 that there is a good safety margin from the maximum ju nction temperature of the mosfet. 4.1 start sequence as shown in figure 5 , it is during the start sequence that, as the ic supply voltage v cc reaches v ccon , the half-bridge starts os cillating and the charge c apacitor connected to tch begins charging. when the voltage at the tch pin reaches vchp (4.63 v), the same capacitor is discharged following an exponential decrease steered by the time constant; this defines the preheating time. during this time, the eoi pin is forced to gro und and the switching frequency is set by the oscillator to the prehe ating value. when the voltage at the tch pin drops down to 1.53 v, the eoi pin is exponentially charged according to a time constant that defines the ignition time. table 2. 4 x 18 w t8 board performance v in (v) p in (w) p outlamp1-2 (w) i in (a) pf thd(%) 85 82.3 34.4 83.6% 0.9 0.99 6 110 80 34.4 86% 0.997 0.99 4.4 140 78.5 34.4 87.6% 0.555 0.99 5.5 185 78.4 34.4 87.7% 0.424 0.98 6.5 230 77.7 34.4 88.5% 0.344 0.97 8.5 265 77.2 34.4 89.1% 0.301 0.95 10 table 3. 4 x 18 w t8 thermal results of critic system components v in (v) ambient temp (c) temp mos lowside (c) temp mos highside (c) temp mos pfc (c) temp l6585de(c) 85 25 54 55 120 44 110 25 53 54 108 43 140 25 53 54 102 43 185 25 53 54 94 43 230 25 53 54 84 43 265 25 53 54 74.5 43
experimental results AN3040 16/27 doc id 16181 rev 2 at the same time the tch pin goes down to ground. during this phase, the oscillator generates a reduction of the switching frequency; when the voltage at the eoi pin exceeds 1.9 v, the chip enters run mode. figure 5. l6585de startup sequence figure 6 shows the lamp ignition phase, across and through which the voltage and current increase linearly. figure 6. one lamp ignition phase figure 7. lamp voltage and current in run mode condition am05154v1 !-v !-v
AN3040 experimental results doc id 16181 rev 2 17/27 4.2 protections with old lamps, abnormal behavior may occur during run mode as a result of the rectifying effect. this effect relates to a differential increase of the ohmic resistance of the two cathodes. the lamp equivalent resistance is therefore higher when the lamp current flows in one direction than in the other. the current waveform is distorted and the mean value of the lamp current is no longer zero. figure 8 shows the behavior of a dual lamp ballast during a rectifying effect. in the eol pin, as soon as the internal window comparator is triggered by a voltage variation due to the re ctifying effect, the t ch cycle starts, and if at its end the comparator is again triggered, the l6585de stops. figure 8. run mode, rectifying effect when an old lamp is connected to the ballast, the strike voltage is higher than the nominal voltage and may also be higher than the safety threshold. in this case, the lamp can take longer than usual to ignite or may not ignite at all. in both cases, because of the frequency drop, the voltage at the output of the ballast can easily reach dangerous values during this ignition time. the same problem occurs if any one of the la mp?s four tubes is broken: the lamp cannot ignite and the lamp voltage must be limited. figure 9 and figure 10 show how the four-lamp ballast ignites when two lamps are broken. when the preheating time t pre = t tch is finished, the l6585de detects the lost ignition of one of the two lamps and starts reducing the preheating time t tch,reduced . at the end of this time, if one of the four lamps is not ignited, the ic is latched. !-v
experimental results AN3040 18/27 doc id 16181 rev 2 figure 9. ignition phase with broken lamps: case 1 (lamp 1 works, lamp 2 is broken, lamp 3 is broken, lamp 4 works) figure 10. ignition phase with broken lamps: case 2 (lamp 1 is broken, lamp 2 works, lamp 3 is broken, lamp 4 works) the hb choke saturation protection has also been tested. because of the intense current, a very high v hbcs is present; the 2.75 threshold trigge rs this event and immediately stops the ic. 4.3 conducted emissions test conducted emissions have been measured in neutral and line wires, using a peak detector and considering the limits for lighting applicat ions specified in en55015. the measurements have been performed at 110 and 230 vac lines. the results are shown in figure 11 , 12 , 13 , 14 and 15 . since the emission level is below both the quasi-peak and average limits with acceptable margin, the power supply passes the pre-compliance test. !-v !-v
AN3040 experimental results doc id 16181 rev 2 19/27 figure 11. conducted emissions at 110 vac 50 hz - line 1 peak detector figure 12. conducted emissions at 110 vac 50 hz - line 2 peak detector figure 13. conducted emissions at 230 vac 50 hz - line 1 peak detector !-v - x q 5 h i g % m 9 $ w w h q g % 3 h d n / r j g % : 6 6 ) & $ $ 6 w d u w n + ] 5 h v % : n + ]9 % : n + ] 6 w r s 0 + ] 6 z h h s p v s w v !-v - x q 5 h i g % m 9 $ w w h q g % 3 h d n / r j g % : 6 6 ) & $ $ 6 w d u w n + ] 5 h v % : n + ]9 % : n + ] 6 w r s 0 + ] 6 z h h s p v s w v !-v - x q 5 h i g % m 9 $ w w h q g % 3 h d n / r j g % : 6 6 ) & $ $ 6 w d u w n + ] 5 h v % : n + ]9 % : n + ] 6 w r s 0 + ] 6 z h h s p v s w v
experimental results AN3040 20/27 doc id 16181 rev 2 figure 14. conducted emissions at 230 vac 50 hz - line 2 peak detector 4.4 guidelines for connecting the four lamps to the ballast the presence of four lamps involves several wi res. the following is a simple schematic that shows how to correctly connect all four lamps to the ballast. figure 15. connecting four lamps to the ballast !-v - x q 5 h i g % m 9 $ w w h q g % 3 h d n / r j g % : 6 6 ) & $ $ 6 w d u w n + ] 5 h v % : n + ]9 % : n + ] 6 w r s 0 + ] 6 z h h s p v s w v !-v /dps /dps /dps /dps output connector "allast output connector "allast
AN3040 automatic restart circuit for lamp replacement doc id 16181 rev 2 21/27 5 automatic restart circuit for lamp replacement the following circuit can be added to the steval-ilb008v1 to implement the automatic restart feature for lamp replacement. figure 16. automatic restart circuit !-v 5 n2kp 5 n2kp ' q & q) 5 n2kp 8 0+& ' 9 & q ) 5 n2kp ' q 5 n2kp 5 n2kp $xwrpdwlf5hvwduw&lufxlw 8 %& 5 n2kp 5 n2kp ' 9 & q ) 6wduwxsqhw /$03 5 02kp /$03 2xwsxw'lrgh%ulgjh /$03 8 %& %orfn fdsdflwru 9ff /'( 9ff /'( 2xwsxw'lrgh%ulgjh 5 n2kp 6wduwxsqhw 5 n2kp ' 9 & q) (2/flufxlw 8$ 0+&% 5 n2kp 5 n2kp ' q 6wduwxsqhw & q) /$03 7/dps: /suhk p +$upv 7/dps: & q)9 7/dps: /suhk p+$upv 7/dps: 5 n2kp & q)9 6wduwxsqhw (2/flufxlw 5 02kp %orfn fdsdflwru ' 9 & q) 5 n2kp ' q 5 n2kp 5 n2kp
bill of materials AN3040 22/27 doc id 16181 rev 2 6 bill of materials table 4. 4 x 18 w t8 bill of materials ref. value type package manufacturer manuf. code rs distrelec other code c1 450 v, 33 f, 20% electrolytic th radial epcos b43851f5336m000 c2 25 v, 560 nf ceramic smd 0805 any c3 25 v, 33 nf ceramic smd 0805 any c4 630 v, 680 nf, 10% polyester th radial epcos b32524q8684k00 0 c5 25 v, 1 nf, 5% cog ceramic smd 0805 any c6 25 v, 330 nf, 10% x7r ceramic smd 0805 any c7 25 v, 1f, 10% ceramic smd 0805 any c8 25 v, 10 nf, 10% ceramic smd 0805 any c9,c14 2000 v, 4.7 nf, 5% polypropylene th radial epcos b32672l8472j000 c10,c11 305 vac x 2, 220 nf, 10% polypropylene th radial epcos b32922c3224k000 c12,c15 400 v, 100 nf, 10% polyester th radial epcos b32561j6104k000 c13 50 v, 100 nf ceramic smd1206 any c16 630 v, 680 pf polypropylene th radial wima 823241 distrelec c17 50 v, 4.7 f electrolytic lead spacing 2.5 5xh11 th radial c18 50 v, 100 nf ceramic smd 0805 any c20 250vac y1, 1 nf th radial 214-5896 c22 630 v, 1 nf ceramic evox rifa 240-4836 rs c25 not mounted smd 0805 any c26,c27 25 v, 22 pf smd 0805 any d2 600 v, 1 a, stth1l06 tu r b o 2 ultrafast high volt rectifier do-41 stmicroelectronics d3,d4,d 5,d6 1000 v, 1 a, gf1m do-214ba vishay 6291123 rs
AN3040 bill of materials doc id 16181 rev 2 23/27 d7, d8 75 v, 150 ma, ll4148 switching diode sod-80 diotec 601496 distrelec d9 16 v, 500 mw voltage regulator diode sod-80 general semiconductor 600819 distrelec d11,d12 100 v, 100 ma, tmmbat41 small signal schottky diode sod323 stmicroelectronics d16, d18 5.1 v, 500 mw voltage regulator diode sod80c 508-674 rs d17, d19 10 v, 500 mw voltage regulator diode sod123 545-3128 rs f1 3 a 377-2180 rs j1 500 v, 32 a, con3 189-5972 rs lamp1,la mp2- lamp3,la mp4 t8 lamp 1, 18 w 141429 distrelec lpfc1 1 a, 8 mh magnetica 1646-0004 lpreh1,l preh2 250 v, 1.4 a, 10 mh lead spacing 10x12.5 (mm) epcos b82732r2142b030 l1,l2 0.5 a, 2.2 mh magnetica 1646.005 lc 250 v, 1.3 a, 2 x 47 mh lead spacing 15x12.5 (mm) epcos b82734r2132b030 q2,q4 std7n52k3 n-channel 525 v, 0.84 , 6.2 a supermesh3 power mosfet dpak stmicroelectronics std7n52k3 q3 std14nm50n n-channel, 500 v, 0.246 , 12 a, mdmesh ii power mosfet dpak stmicroelectronics std14nm50n r5 750 k , 5%, 1/4 w th radial any table 4. 4 x 18 w t8 bill of materials (continued) ref. value type package manufacturer manuf. code rs distrelec other code
bill of materials AN3040 24/27 doc id 16181 rev 2 r9 750 k , 5 % , 1/4 w smd1206 any r6,r11 1.5 m , 5%, 1/4 w smd 1206 any r7,r12 910 k , 5%, 1/4 w smd 1206 any r10 68 k , 5%, 1/4 w th radial any r13 47 k , 5% , 1/8 w smd 0805 any r14 33 k , 5%, 1/8 w smd 0805 any r15 750 k , 5%, 1/8 w smd 0805 any r16 75 k , 5%, 1/8 w smd 0805 any r17 7.5 k , 5%, 1/4 w smd 1206 any r18 18 k , 5%, 1/4 w smd1206 any r19 13 k , 5%, 1/4 w smd1206 any r20,r23 43 , 5%, 1/8 w smd 0805 any r21 100 , 5%, 1/8 w smd 0805 any r22 0.150 , 1%, 1 w th radial any r29 10 , 5%, 1/4 w smd 1206 any r31 0.47 , 1%, 1 w th radial any r34 470 k p a r a l l e l 470 k , 5%, 1/4 w smd 1206 any r35 220 k , 5%, 1/2 w th radial any r36,r40 150 k , 5%, 1/4 w th radial any r37,r41 150 k , 5%, 1/4 w smd 1206 any table 4. 4 x 18 w t8 bill of materials (continued) ref. value type package manufacturer manuf. code rs distrelec other code
AN3040 bill of materials doc id 16181 rev 2 25/27 r52,r53, r59,r69 0 , 5%, 1/4 w smd 1206 any r60,r68 1.5 m , 5%, 1/4 w smd 1206 any r66,r67 1.8 m , 5%, 1/8 w smd 1206 any u1 l6585de combo ic for pfc and ballast control stmicroelectronics l6585de table 4. 4 x 18 w t8 bill of materials (continued) ref. value type package manufacturer manuf. code rs distrelec other code
revision history AN3040 26/27 doc id 16181 rev 2 7 revision history table 5. document revision history date revision changes 16-apr-2010 1 initial release. 11-jun-2010 2 modified: section 3.1
AN3040 doc id 16181 rev 2 27/27 please read carefully: information in this document is provided solely in connection with st products. stmicroelectronics nv and its subsidiaries (?st ?) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described he rein at any time, without notice. all st products are sold pursuant to st?s terms and conditions of sale. purchasers are solely responsible for the choice, selection and use of the st products and services described herein, and st as sumes no liability whatsoever relating to the choice, selection or use of the st products and services described herein. no license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. i f any part of this document refers to any third party products or services it shall not be deemed a license grant by st for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoev er of such third party products or services or any intellectual property contained therein. unless otherwise set forth in st?s terms and conditions of sale st disclaims any express or implied warranty with respect to the use and/or sale of st products including without limitation implied warranties of merchantability, fitness for a parti cular purpose (and their equivalents under the laws of any jurisdiction), or infringement of any patent, copyright or other intellectual property right. unless expressly approved in writing by an authorized st representative, st products are not recommended, authorized or warranted for use in milita ry, air craft, space, life saving, or life sustaining applications, nor in products or systems where failure or malfunction may result in personal injury, death, or severe property or environmental damage. st products which are not specified as "automotive grade" may only be used in automotive applications at user?s own risk. resale of st products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by st for the st product or service described herein and shall not create or extend in any manner whatsoev er, any liability of st. st and the st logo are trademarks or registered trademarks of st in various countries. information in this document supersedes and replaces all information previously supplied. the st logo is a registered trademark of stmicroelectronics. all other names are the property of their respective owners. ? 2010 stmicroelectronics - all rights reserved stmicroelectronics group of companies australia - belgium - brazil - canada - china - czech republic - finland - france - germany - hong kong - india - israel - ital y - japan - malaysia - malta - morocco - philippines - singapore - spain - sweden - switzerland - united kingdom - united states of america www.st.com

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