touch control halogen lamp dimmer 1 2 3 4 5 6 7 8 ls7631 ls7632 v dd (+v) mode cap sync trig v ss (-v) ext sens figure 1 lsi features: touch or pushbutton control of incandescent lamps and transformer-coupled halogen lamps ?transformer can be magnetic or electronic direct replacement for p/n slb 0587 ?automatic safety shutdown pll synchronization allows use as a wall switch three operating modes extension input for remote activation 50hz/60hz ac line frequency +5v power supply (v dd - v ss ) ls7631, ls7632 (dip); LS7631-S, ls7632-s (soic) 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 ls7631/ls7632 cmos ics as follows: 1. compensation for 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. compensation for delayed triac turn-on. at the set conduction angle, a triac trigger pulse of 130.2? (60 hz) is issued by the ic. if the triac fails to fire, a second trigger pulse of 260.4? width is issued 1ms later as a second attempt to fire the triac during the same half-cycle. 3. safety-shutdown. if the frequency of occurrences of the delayed cut-off and 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 cut-off or 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 both ls7631 and ls7632 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 cap (pin 3) - pll filter capacitor input. see figure 6. sync (pin 4) - see figure 6 the ac line frequency is applied to this input. all internal timings are synchronized to the ac phase through a pll circuit. 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. november 2002 7631/7632-112002-1 lsi/csi lsi computer systems, inc. 1235 walt whitman road, melville, ny 11747 (631) 271-0400 fax (631) 271-0405 ls7631/7632 u l a3800 pin assignment - top view
the functional differences between ls7631 and ls7632 are: ls7631 - when a long touch is applied, the dimming direction auto- matically reverses whenever maximum or minimum conduction an- gles are reached. ls7632 - when a long touch is applied, the dimming stops when- ever 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 ? /4.17ms (60hz). there are a total of 84 discrete values of ? 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. 7631/7632-111902-2 ls7632 note : if the user applies a long touch when the trig conduction angle is within a ?ew?degrees of maximum or minimum, the trig conduction angle can move to maximum or minimum and stop without the user being able to observe a change in brightness. therefore, the user should be instructed that if no change in bright- ness is observed in response to a long touch, the long touch should be removed and reapplied in order to produce a change in brightness. 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: (ta = +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 unit 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 tw - 130.2 - ? 60hz tw - 156.2 - ? 50hz conduction angle 41 - 158 deg - ?incremental steps d - 1.4 - deg - (note 1) soft-on slew rate s s - 1.4 - deg/4.17ms 60hz s s - 1.4 - deg/5ms 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 = 83. note 2 : number of steps from a0 to a1, or a2 to a0 = 68. note 3 : number of steps from a1 to b1 or b2 to a2 = 15. note 4 : ?is at minimum between b1 and b2. t bd is applicable for ls7631 only. for ls7632 when minimum ?is reached, dimming direction reverses only if the long touch is terminated and reapplied. 7631/7632-112102-3 150 100 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 figure 3. ls7631 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. replacement for p/n slb 0587 ls7631 and ls7632 can be used in place of the slb 0587 without modifying the application circuit recommended by the manufacturer of that ic.
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 figure 4. ls7632 trig, vs touch (sens or ext) 7631/32-112102-4 ext 10k w in914 touch plate *r 200k w mps8599 figure 7. electronic extension *r p *r = 2m w for 115vac *r = 3.6m w for 220vac all resistors 1/4w 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 7. 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 6) application example: a typical implementation of the light dimmer circuit is shown in fig. 6. 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 c5. r2 and c4 generate the filtered signal for the sync input for synchronizing the internal pll with the line frequency. r3 and c6 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. c3 is the filter capacitor for the internal pll. r8 provides current limiting and isolation between the chip output and the triac gate. c1 and l are rfi filter circuits. p 115vac or 220vac n lamp c1 t l c2 r1 r2 r8 r3 c5 d1 1 2 3 4 8 7 6 5 r4 c3 c4 trig v ss ext sens v dd mode cap sync + ls7631/ls7632 r6 r5 figure 6. a typical halogen lamp dimmer wall switch g mt2 mt1 z - electronic extension (fig. 7) extn p c6 see note 3 see note 2 r7 touch plate see note 4 c1 = 0.15?, 200v c1 = 0.15?, 400v c2 = 0.15?, 200v c2 = 0.082?, 400v c3 = 0.02?, 12v c4 = 0.002?, 12v c5 = 100?, 12v c6 = 0.1?, 12v r1 = 270 w , 1/2w r1 = 1k w , 1w r2 = 680 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 = 100? (rfi filter) l = 200? (rfi filter) (1) for loads greater than 6a, use an alternistor . = component change for 220vac * * * * * * * * notes 1. all circuits connected by broken lines are optional. 2. c6 is used only with electronic extension and r7 is used only with a pushbutton. 3. connection between pin 6 & pin 7 should be broken when ext is used. 4. as a precaution, transformer should have thermal protection.
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