touch control halogen lamp dimmer features: touch or pushbutton control of incandescent lamps and transformer-coupled halogen lamps ?works with magnetic or electronictransformers ?automatic safety shutdown three operating modes extension input for remote activation 50hz/60hz ac line frequency ?+5v power supply (v dd - v ss ) ls7634, LS7635 (dip); ls7634-s, LS7635-s (soic); ls7634fo, LS7635fo (dip); ls7634fo-s, LS7635fo-s (soic) - see figure 1 - applications: electronic dimmers for wall switch control of ceiling mounted lighting, foot switch control of large floor lamps and hand switch control of table lamps. background and general description: a typical electronic dimmer may not operate properly with the in- ductive load encountered when driving a transformer-coupled low-voltage halogen lamp. the inductive load can cause a phenomenon called half-waving, wherein the triac fires in al- ternate half-cycles only, which may lead to the thermal de- struction of the load transformer. the problems encountered in driving an inductive load are addressed by the ls7634/LS7635 family of cmos ics as follows: 1. delayed triac cut-off. when a trigger pulse is due to occur at a conduction angle which coincides with the on-state of the triac, the trigger pulse is delayed until the triac has turned off. this eliminates the underlying cause of half-waving. 2. delayed triac turn-on and safety shutdown with inductive loads, the holding current needed to maintain the triac on-state, may seriously lag behind the gate trigger signal causing the triac to turn off prematurely. if the frequency of occurrences of the delayed turn-on exceeds a preset threshold, a shutdown is initiated by turning off the triac trigger pulses. the safety-shutdown threshold value is accumulated in a 4-bit up/down counter. the count increments for every occurrence of delayed turn-on and decrements once every 8 sync pulses (ac line cycles). the counter will not decrement below zero. if the count reaches 15, the safety-shut-down is effected. input/output description: v dd (pin 1) supply voltage positive terminal. vss (pin 7) supply voltage negative terminal. mode (pin 2) - see table 1 all variations of ls7634 and LS7635 can operate in 3 different modes. the 3-state mode input selects the operating modes: vss = mode 0; float = mode 1; v dd = mode 2 sync (pin 4) - see figure 6 the ac line frequency is applied to this input. all internal timings are synchronized to the ac. the load on/off status information is also derived from this input. sens (pin 5) - see table 1 a logic 0 applied to this input alters the trig output either by turning it on, turning it off or by changing its conduction angle. specifically which action takes place is dependent on the type of activation of the sens input, namely short or long touch and the prior state of trig output. ext (pin 6) same functionality as the sens input, except that a logic 1 is the active level at this input. ext input is intended to be operated from a remote site with long cable connection, when noise can be expected. the sampling method used at this input makes it less sensitive to noise. trig (pin 8) the trig output is a low level pulse occurring once every half- cycle of the ac and is intended to drive the gate of a triac in se- ries with the load. the conduction angle, ? of the trig pulse can be varied by means of long and short touches at either the sens or the ext input. test (pin 3) for factory use only. september 2006 7634/7635-090606-1 lsi/csi l si c o m p u t e r sy s t e m s , i n c . 1 2 3 5 w a l t w h i t m a n r o a d , m e l v i l l e , n y 1 1 7 4 7 ( 6 3 1 ) 2 7 1 - 0 4 0 0 f a x ( 6 3 1 ) 2 7 1 - 0 4 0 5 u l a3800 ls7634 LS7635 ls7634fo LS7635fo lsi 1 2 3 4 8 7 6 5 v ss ( -v ) ext v dd ( +v ) mode sync figure 1 trig sens ls7634 LS7635 pin assignment - top view test
the differences among all versions of ls7634 and LS7635 are: ls7634 (ls7634fo) upon power-up, the trig output is off. (upon power-up, the trig output is on at maximum conduction angle.) when a long touch is applied, the dimming direction automatically re- verses whenever maximum or minimum conduction angles are reached. LS7635 (LS7635fo) upon power-up, the trig output is off. (upon power-up, the trig output is on at maximum conduction angle.) when a long touch is applied, the dimming stops whenever maximum or minimum conduction angles are reached. in order to change dimming levels from maximum or minimum, long touch must be removed and reapplied.the purpose of this feature is to allow the user to positively locate maximum and minimum conduction angles. table 1 mode short touch long touch dimming reversal pre-touch post-touch pre-touch post-touch (note 5) off max(note 1) off/min varies up from min n/a 0 on off max varies down from max n/a intermediate varies from intermediate no off memory off varies from memory (notes 2, 3,4) yes 1 (notes 2, 3) min varies up from min n/a on off max varies down from max n/a intermediate varies from intermediate yes off max (note 1) off/min varies up from min n/a 2 on off max varies down from max n/a intermediate varies from intermediate yes note 1 : a soft turn-on is produced by slewing up the conduction angle, ? from minimum at the rate of 1.4 ? /8.33ms (60hz). note 2 : a soft turn-on is produced by slewing up ? from minimum to memory. upon power-up the memory value is defaulted to maximum conduction angle. note 3 : ?emory?refers to the conduction angle, ? which existed prior to the current off-state. note 4 : a soft turn-on is produced by slewing up ? from minimum to memory upon which the dimming is started. note 5: no = dimming direction does not reverse from prior dimming direction. yes = dimming direction does reverse from prior dimming direction. n/a = does not apply. 7634/7635-010906-2 LS7635 note : if the user applies a long touch when the trig conduc- tion angle is within a ?ew?degrees of maximum or mini- mum, the trig conduction angle can move to maximum or minimum and stop without the user being able to observe a change in brightness. there-fore, the user should be in- structed that if no change in brightness is observed in re- sponse to a long touch, the long touch should be re moved and reapplied in order to produce a change in bright- ness. absolute maximum ratings: parameter symbol value unit dc supply voltage v dd - vss +7 v any input voltage v in vss - 0.3 to v dd + 0.3 v operating temperature t a 0 to +90 ? storage temperature t stg -65 to +150 ? dc electrical characteristics: (t a = +25?c, all voltages referenced to vss. v dd = +5v unless otherwise noted.) parameter symbol min typ max unit condition supply voltage v dd 4.5 5.0 5.5 v - supply current i dd - 300 400 ? output unloaded v dd = 5.5v sync lo v isl - - 2.1 v - sync hi v ish 2.9 - - v - ext, sens lo v iel - - 1.5 v - ext, sens h i v ieh 3.5 - - v - trig lo v ol - 0.2 - v - trig h i v oh - 5.0 - v - trig sink current i tsnk 35 - - ma v otrig = 2.5v
timing characteristics (see figures 2, 3 and 4) : parameter symbol min typ max uni t condition sync frequency fs 40 - 70 hz - short touch t si 42 - 333 ms 60hz t si 50 - 400 ms 50hz long touch t s2 342 - infinite ms 60hz t s2 410 - infinite ms 50hz trig pulse width (see note 5) tw - 130 - ? 60hz tw - 156 - ? 50hz conduction angle 50 - 154 deg - ?incremental steps d - 1.4 - deg - (note 1) soft-on slew rate s s - 1.4 - deg/8.33ms 60hz s s - 1.4 - deg/10ms 50hz a0 to a1/a2 to a0 slew rate s aa - 1.4 - deg/33.3ms 60hz (note 2) s aa - 1.4 - deg/40ms 50hz a1 to b1/b2 to a2 slew rate s ba - 1.4 - deg/66.7ms 60hz (note 3) s ba - 1.4 - deg/80ms 50hz b1 to b2 delay t bd - 500 - ms 60hz (note 4) t bd - 600 - ms 50hz note 1 : total number of steps = 77. note 2 : number of steps from a0 to a1, or a2 to a0 = 55. note 3 : number of steps from a1 to b1 or b2 to a2 = 21. note 4 : ?is at minimum between b1 and b2. t bd is applicable for ls7634 only. for LS7635 when minimum ?is reached, dimming direction reverses only if the long touch is terminated and reapplied. note 5: t w = 488us (60hz), 586us (50hz) available. contact factory for details. 7634/7635-071406-3 figure 3. ls7634 trig, vs touch (sens or ext) trig sync t w figure 2. trig output conduction angle, the information included herein is believed to be accurate and reliable. however, lsi computer systems, inc. assumes no responsibilities for inaccuracies, nor for any infringements of patent rights of others which may result from its use. 150 100 50 off 150 100 50 off 150 100 50 off mode mode 1 mode 2 sens t s1 t s2 342ms short short long short long short long a2 b2 b1 a1 a0 a2 b2 b1 a2 b2 b1 a1 a0 a0 a0 a1 a2 a2 slope = s ba memory reverse reverse slope = ss slopes = s aa b2 b2
figure 4. LS7635 trig, vs touch (sens or ext) extensions: all switching and dimming functions can be implemented by utilizing the ext input. use a pushbutton or the electronic switch in conjunction with a touch plate as shown in figure 6. when the plate is touched, a logic high level is generated at the ext input of the ic for both half- cycles of the line frequency. (see figure 5) application example: a typical implementation of the light dimmer circuit is shown in fig. 5. here the brightness of the lamp is set by touching the touch plate. the function of different components are as follows: the 5v dc supply for the chip is provided by z, d1, r1, c2 and c4. r2 and c3 generate the filtered signal for the sync input ac phase synchronization. r3 and c5 act as a filter circuit for the electronic extension. if extensions are not used, the ext input (pin 6) should be tied to vss (pin 7). r4, r5 and r6 set up the sensitivity of the sens input. r8 provides current limiting and isolation between the chip output and the triac gate. c1 and l are rfi filter circuits. c1 = 0.15f, 200v c1 = 0.15f, 400v c2 = 0.22f, 200v c2 = 0.15f, 400v c3 = 0.002f, 10v * component change for 220vac ** snubber network (see note 5) c4 = 100f, 10v c5 = 0.1f, 10v r1 = 270 w , 1/2w r1 = 1k w , 1w r2 = 680k w , 1/4w r2 = 1.5m w , 1/4w r3 = 1.5m w , 1/4w r4 = 1m w to 5m w , 1/4w (select for sensitivity) r5, r6 = 2.7m w , 1/4w r5, r6 = 4.7m w , 1/4w r7 = 150k w , 1/4w r8 = 62 w , 1/4w d1 = 1n4148 z = 5.6v, 1w (zener) t = q4004l4 typical triac (1) t = q5003l4 typical triac (1) l = 100h (rfi filter) l = 200h (rfi filter) (1) for loads greater than 6a, use an alternistor . * * * * * * * ext 10k w in914 touch plate *r 200k w mps8599 figure 6. electronic extension *r p *r = 2m w for 115vac *r = 3.6m w for 220vac all resistors 1/4w 150? 100? 50? off 150? 100? 50? off 150? 100? 50? off mode mode 1 mode 2 t s1 t s2 342ms short short slope = s s slope = s aa slope = s ba long long long long a2 a0 a0 a1 b1 b2 a2 a2 b2 b1 a1 a2 b2 b1 a1 a0 a0 a0 a0 a2 a2 memory a2 memory short short reverse reverse sens long b2 b2 b2 b2 7634/7635-090606-4 p 115vac or 220vac n lamp c1 t l c2 r1 r2 r8 r3 c4 d1 8 7 6 5 r4 c3 trig v ss ext sens v dd mode sync + ls7634 / LS7635 r6 r5 figure 5. a typical halogen lamp dimmer wall switch g mt2 mt1 z - electronic extension (fig. 7) extn p c5 see note 3 see note 2 r7 notes 1. all circuits connected by broken lines are optional. 2. c5 is used only with electronic extension and r7 is used only with mechanical switch. 3. connection between pin 6 & pin 7 should be broken when ext is used. 4. magnetic transformer should have thermal protection. 5. some electronic transformers may require larger values of c2, sensitive gate triacs and snubber networks. c2 values may have to be adjusted to be as high as 0.47uf for 115vac and 0.33uf for 220vac. the sensitive gate triacs are chosen for their low holding current. typical triacs are l4004l6 and l6 004l6 for 115vac and 220vac applications, respectively. **c6-r9 is the snubber network: c6 = 0.1uf, 200v, r9 = 1k ohm, 1/2w (115vac); c6 = 0.05uf, 400v, r9 = 1k ohm, 1w (220vac) touch plate see note 4 test 1 2 3 4 **r9 **c6
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