application note l6560/a pfc in lamp ballast applications the l6560 ic is especially designed to be used in lighting applications. in fact, the ic is very simple to use and its needs, in terms of external compo- nents, are minimized. information about the use of the ic is given in the an667; this section pre- sents an overview of some circuits for ballast ap- plications using l6560 in several configuration. the first application (see fig 1) is a standard boost topology suitable for high mains input with the tar- get specifications as follows: rated mains v in(rms) = 277 vac (+10% -15%) max. output power p o = 140w output voltage v o = 450v AN830/0896 8 3 bridge 4 x by255 r9 1.8m 5% c1 0.22 m f 630v r10 6.2k 5% c2 22 m f 25v fuse vac r1 68k 5% t 5 6 l6560 7 21 c3 0.47 m f/1 m f r5 10 mos stp6n60 r4 330 4 d1 byt13-600 r7 1.1m 1% c5 47 m f/68 m f 250v vo=450v po=140w + - d95in260a transformer t: core thomson-csf b1et2910a primary 90t of litz wire 10 x 0.2mm secondary 7t of #32 awg (0.15mm) gapped for a total primary inductance of 560 m h r6 0.68 500mw r8 6.15k 1% c4 1nf + - c6 10nf 277v +10% -15% v cc r9 510k 5% r10 510k 5% c6 47 m f/68 m f 250v figure 1: v mains = 277vac, v o = 450v, p o = 140w 8 3 bridge 4 x by255 r9 1.8m 5% c1 0.1 m f 630v r10 6.2k 5% c2 22 m f 25v fuse vac r1 68k 5% t 5 6 l6560 7 21 c3 0.47 m f/1 m f r5 10 mos stp4na60 r4 330 4 d1 byt13-600 r7 1.1m 1% vo=450v po=70w + - d95in261a transformer t: core thomson-csf b1et2910a primary 90t of litz wire 10 x 0.2mm secondary 7t of #32 awg (0.15mm) gapped for a total primary inductance of 710 m h r6 1.5 250mw r8 6.15k 1% c4 1nf + - c6 10nf 277v +10% -15% v cc c5 22 m f/47 m f 250v r9 620k 5% r10 620k 5% c6 22 m f/47 m f 250v figure 2: v mains = 277vac, v o = 450v, p o = 70w the second one (see fig 2) is still a boost topol- ogy with high mains input but it has a lower output power. the target specifications are: rated mains v in(rms) = 277 vac (+10% -15%) max. output power p o = 70w output voltage v o = 450v 1/4
note: the core of the transformer is oversized for the rated power, etd core is generally an oeasy to useo low cost solution. for both the above described circuits, to sustain the high output voltage value, we suggest using two capacitor connected in series, 250v rated voltage each one. the third solution (see fig 3) shows the same pfc configuration for a lower rated input mains, directed to a different market area. it can be noticed the lower rated parameter of some external components like mos, d1, c1 and c5. the target specifications are: rated mains v in(rms) = 120 20% vac max. output power p o = 70w output voltage v o = 230v 8 3 bridge 4 x by255 r9 1.8m 5% c1 0.22 m f 630v r10 6.2k 5% c2 22 m f 25v fuse vac r1 68k 5% t 5 6 l6560 7 21 c3 330nf r5 10 mos stp5n80 r4 330 4 d1 byt13-800 r2 1.3m 1% vo=320v po=140w + - d95in263a transformer t: core thomson-csf b1et2910a primary 150t of litz wire 10 x 0.2mm secondary 7t of #32 awg (0.15mm) primary inductance: 3mh r6 0.47 1w r8 12k 1% c4 1nf + - c6 10nf 277v +10% -15% v cc r12 330k r11 62k 1% c5 82 m f/100 m f 385v 3 2 4 v cc r3 12k 1% 8 lm358 a r7 1.3m 1% + - figure 4: v mains = 277vac, v o = 320v, p o = 140w, buck-boost topology 8 3 bridge 4 x by255 r9 1.8m 5% c1 0.47 m f 250v r10 16k 5% c2 22 m f 25v fuse vac r1 68k 5% t 5 6 l6560 7 21 c3 0.47 m f/1 m f r5 10 mos stp5n30 r4 330 4 d1 byt03-400 r7 1.1m 1% c5 47 m f/82 m f 315v vo=230v po=70w + - d95in262 transformer t: core thomson-csf b1et2910a primary 90t of litz wire 10 x 0.2mm secondary 7t of #32 awg (0.15mm) gapped for a total primary inductance of 700 m h r6 0.5 250mw r8 12k 1% c4 1nf + - c6 10nf 120v 20% v cc figure 3: v mains = 120vac, v o = 230v, p o = 70w here it is shown a different topology (see fig 4), suitable for pfc in lighting, that allows to keep the output voltage at an advantageous value even if the rated input mains value is high. this has been realized using a olevel shift configura- tiono the target specifications are: rated mains v in(rms) = 277vac (+10% - 15%) max. output power p o = 140w output voltage v o = 320v application note 2/4
finally, fig. 6 shows a block diagram of a common electronic ballast. the pfc section is based on the already described l6560 pfc controller, and the ballast section is based on the l6569, high voltage push-pull gate driver. 8 3 bridge 4 x by255 r2 1.8m 5% c1 0.22 m f 630v r3 6.2k 5% c2 22 m f 25v fuse vac r1 68k 5% l1 5 6 l6560 7 21 c3 330nf r5 10 mos stp5n80 r4 330 4 d1 byt13-800 vo=320v po=140w + - d95in264a inductors core thomson-csf b1et2910a l1: primary 100/110t of litz wire 10 x 0.2mm l2: same as l1 l3: secondary 7t of #32 awg (0.15mm) r6 0.47 1w r8 12k 1% c4 1nf + - c6 10nf 277v +10% -15% v cc c5 82 m f/100 m f 385v r7 1.3m 1% l3 l2 figure 5: circuit with v mains = 277vac, v o = 320v, p o = 140w, flyback topology note: this topology involves a peak inductor cur- rent higher than in the standard boost topology, so a bigger emi filter is neces- sary. an external e/a is used to shift the output feedback. the ground of the pfc section is not the same of the ballast one. a flyback topology (see fig 5), allows the same advantages as the previous application with level shift configuration but with a common ground. the target specifications are: rated mains v in(rms) = 277vac (+10% - 15%) max. output power p o = 140w output voltage v o = 320v note: this last topology involves higher peak cur- rent in the transformer in comparison with the standard boost topology, this requiring a bigger emi filter. the transformer assem- bly is more complicated than the inductor with the auxiliary winding used for the other applications. l6569 hvhb driver boot r f c f c vs v s hvg out lvg gnd l6560 p.f.c. c boot 220v ac r vh 400vdc d95in306a figure 6 : electronic ballast. application note 3/4
information furnished is believed to be accurate and reliable. however, sgs-thomson microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of sgs-thomson microelectronics. specification mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. sgs- thomson microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of sgs-thomson microelectronics. ? 1996 sgs-thomson microelectronics printed in italy all rights reserved sgs-thomson microelectronics group of companies australia - brazil - canada - china - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco - the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. application note 4/4
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