reverse phase (trailing-edge) halogen lamp dimmer features: pushbutton or touch control of high-voltage lamps and all electronic transformer-coupled low-voltage halogen lamps. ?controls fluorescents and cfls via dimming ballasts. ?reverse-phase technology eliminates rfi generation. ? fo " versions power up f ull o n after application of ac. ?soft turn-on and soft turn-off three operating modes. inputs for direct or remote activation. 50hz/60hz ac line frequency. ?+12v power supply (v dd - v ss ). ls7636 , ls7637 (dip); ls7636-s , ls7637-s (soic); ls7636fo , LS7637FO (dip); ls7636fo-s , LS7637FO-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: since the operating currents of some electronic transformers are below the holding current of most triacs, a typical triac- based (leading-edge) dimmer may not operate properly when driving an electronic transformer-coupled low-voltage halogen lamp. the filtering components in the electronic transformer which prevent its operating frequency from generating line in- terference can also inhibit triac triggering. the ls7636_ls7637 family of reverse-phase dimmer ics drive fets or igbts (see figure 3 and figure 4) and ?lowly?turns on current beginning at the ac input zero-crossing. this ?low current turn on is ideal for interfacing with the primary of any electronic transformer and also eliminates the rfi generation caused by the sudden turn on of current when using a triac- based dimmer. input/output description: v dd (pin 1) supply voltage positive terminal. v ss (pin 7) supply voltage negative terminal. mode (pin 2) - see table 1 all variations of ls7636 and ls7637 can operate in 3 different modes. the 3-state mode input selects the operating modes: v ss = mode 0; float = mode 1; v dd = mode 2 sync (pin 4) - see figure 2 the ac line frequency is applied to this input. all internal timings are synchronized to the ac. sens (pin 5) - see table 1 a logic 0 applied to this input alters the gate drive 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 duration and the prior state of the gate drive output. ovc - overcurrent sense input (pin 6) the voltage at this input is sampled every half-cycle in a four-cycle period. if the voltage reaches the ovc threshold four times, then the gate output is turned off shutting down the current through the load. six cycles after shutdown occurs, the output is turned on to the previous conduction angle, the ovc counter is reset and a new four-cycle period begins. the ovc voltage may be generated with a fractional-ohm resistor as shown in figure 4 and figure 5. when ovc is not being used, pin 6 must be tied to pin 7. gate (pin 8) the gate drive output is a positive-going pulse that initiates at every zero-crossing of the ac input. the width of the gate drive signal determines the conduction angle as shown in figure 2. test (pin 3) for factory use only. june 2009 7636-061009-1 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 ls7636 ls7637 ls7636fo LS7637FO 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. lsi 1 2 3 4 8 7 6 5 v ss ( -v ) ovc v dd ( +v ) mode sync figure 1 gate sens ls7636 ls7637 pin assignment - top view test
timing characteristics (see figures 2, 3 and 4): parameter symbol min typ max unit condition sync frequency f s 40 - 70 hz - short activation t s1 50 - 417 ms 60hz t s1 60 - 500 ms 50hz long activation t s2 433 - infinite ms 60hz t s2 520 - infinite ms 50hz gate drive pulse width gdw 2.31 - 7.13 ms 60hz (see note 5) gdw 2.78 - 8.56 ms 50hz conduction angle 50 - 154 deg - incremental steps d - 1.4 - deg - (note 1) soft-on slew rate s s - 1.4 - deg / 33.3ms 60hz s s - 1.4 - deg / 40ms 50hz a0 to a1/a2 to a0 slew rate s aa - 1.4 - deg / 33.3ms 60hz (note 2) s ba - 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 ls7636 only. note 5: for ls7637 when minimum ?is reached, dimming direction reverses only if the long activation is terminated and reapplied. the difference among all versions of ls7636 and ls7637 are: ls7636 ( ls7636fo ) upon power-up, the gate drive output is off. (upon power-up, the gate drive output is on at maximum conduction angle.) when a long activation is applied, the dimming direction automatically reverses whenever maximum or minimum conduction angles are reached. ls7637 ( LS7637FO ) upon power-up, the gate drive is off. (upon power-up, the gate drive is on at maximum conduc- tion angle.) when a long activation is applied, the dim- ming stops whenever maximum or minimum conduction angles are reached. in order to change dimming levels from maximum or minimum, long activation must be re- moved and reapplied. the purpose of this feature is to al- low the user to positively locate maximum and minimum conduction angles. ls7637 note: if the user applies a long activation when the gate drive conduction angle is within a "few" de- grees of maximum or minimum, the gate drive conduction angle can move to maximum or mini- mum and stop without the user being able to ob- serve a change in brightness. therefore, the user should be instructed that if no change in bright- ness is observed in response to a long activa- tion, the long activation should be removed and reapplied in order to produce a change in bright- ness. 7636-121906-2
table 1 mode short-activation long-activation dimming reversal pre-activation post-activation pre-activation post-activation (note 5) off max (note 1) off/min varies up from min n/a 0 on off (note 4) max varies down from max n/a intermediate varies from intermediate no off memory (notes 2, 3) off/min varies up from min n/a 1 on off (note 4) 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 (note 4) 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 o / 33.3ms (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-off is produced by slewing down ?from the existing conduction angle to off at the rate of 1.4 o / 33.3ms (60hz). 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. 7636-063008-3 absolute maximum ratings: parameter symbol value unit dc supply voltage v dd - v ss +16 v any input voltage v in v ss - 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 ? , all voltages referenced to v s s . v dd = +12v unless otherwise noted.) parameter symbol min typ max unit condition supply voltage v dd 10 12 15 v - supply current i dd - 0.8 1 ma output unloaded v dd = +12v sync lo v isl - - 5.7 v - sync hi v ish 6.4 - - v - sens lo v iel - - 4.5 v - sens h i v ieh 7.7 - - v - gate drive source current i gsr 4 - - ma v oh = 11.5v sink current i gsn 4 - - ma v ol = 0.5v ovc -- 0.35 - v -
a0 a1 b1 b2 short long ts2 short short long a0 a1 b1 b2 a2 a2 memory reversal no reversal no memory no memory reversal ls7636 ts1 no memory no reversal reversal a0 a1 b1 b2 a2 memory no memory reversal ls7637 short short short short long long long long f vs sens 50 100 150 off sens off 50 100 150 mode1 off 50 100 150 mode2 off 50 100 150 mode0 off 50 100 150 150 100 50 off mode1 mode2 f f f f f f mode0 sens ff sync gate f i gure 2. gate c onduction a ngle, 7636?121 8 06? 4 f f i gure 3. gate c onduction a ngle,
7636-041709-5 c1 = 100uf r6 = 150k w d4 = 1n4004 c2 = 0.0047uf r6 = 270k w d5 = 1n4004 c3 = 0.047uf r7 = 47k w q1 = mje340 (or equivalent) c4 = 0.1uf r7 = 91k w q2 = liteon ltv354t (or equivalent) r1 = 150k w r8 = 47k w q3 = irf630 (typical) r1 = 270k w , 1/2w r8 = 91k w q3 = irf730 (typical) r2 = 390 w r9 = 0.25 w , 1w ( for 1 amp rms max) q4 = irf630 (typical) r3 = 39k w r10 = 4.3k w , 1/2w q4 = irf730 (typical) r4 = 1.5m w d1 = 12v, 1/2w, 5% r5 = 10k w d2 = 5.6v, 1/4w, 10% all resistors 1/4w, all capacitors 25v unless otherwise specified d3 = 1n4004 * = component change for 220vac * * * figure 4 . reverse phase dimmer (option 1) * * * v dd mode test sync gate v ss ovc sens/ sense switch 3 4 2 1 q2 r3 + c1 d1 c4 r5 load transformer n p ext switch d2 r2 q1 r1 d4 d3 d5 q4 3 2 1 1 2 3 r9 r6 c3 r4 r7 v dd q3 r8 u3 ls7636 1 2 3 4 5 6 7 8 c2 r10
7636-041709-6 c1 = 100uf r6 = 47k w d3 = 1n4004 c2 = 0.0047uf r6 = 91k w d4 = 1n4004 c3 = 0.047uf r7 = 47k w d5 = df02 c4 = 0.1uf r7 = 91k w d5 = df04 r1 = 150k w r8 = 10k w q1 = mje340 (or equivalent) r1 = 270k w , 1/2w r9 = 0.25 w , 1w ( for 1 amp rms max) q2 = liteon ltv354t (or equivalent) r2 = 390 w r10 = 4.3k w , 1/2w q3 = irf630 (typical) r3 = 39k w d1 = 12v, 1/2w, 5% q3 = irf730 (typical) r4 = 1.5m w d2 = 5.6v, 1/4w, 10% r5 = 150k w all resistors 1/4w, all capacitors 25v unless otherwise specified * = component change for 220vac * * * figure 5 . reverse phase dimmer (option 2) * * v dd mode test sync gate v ss ovc sens/ sense switch 3 4 2 1 q2 c2 r3 + c1d1 c4 r8 load transformer p d2 r2 q1 r1 n r5 c3 r4 r6 v dd 1 2 3 q3 ext switch + - u3 ls7636 r7 d3 d4 r9 d5 1 2 3 4 5 6 7 8 r10
7636-041809-7 v dd touch plate q1 q2 d1 r3 r1 r2 touch output r4 r5 r1 = 1m d1 = 1n4148 r2 = 1m q1 = mps8599 r3 = 220k q2 = mps8099 r4 = 100k r5 = 510k all resistors 1/4w figure 6. application circuit for touch control operation to sens, pin 5 the application circuit shown in figure 6 can be applied to the reverse dimmer cir- cuits shown in figure 4 (option 1) and figure 5 (option 2). the touch output is con- nected to the sense input (pin 5) of ls7636. when using the circuit shown in figure 6, the following components must be removed in figure 4 and figure 5: figure 4 - remove r6, d5, ext switch and sense switch. c3 remains. figure 5 - remove r5, d3, ext switch and sense switch. c3 remains.
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