touch control lamp dimmer description: ls7231 through ls7234 are a series of monolithic, mos integrated circuits designed for the control of brightness of incandescent lamps. the outputs of these ics control the brightness of a lamp by controlling the firing angle of a triac connected in series with the lamp. all internal timings are synchronized with the line frequency by means of a built-in phase-lock loop circuit. the output occurs once every half-cycle of the line frequency. within the half- cycle, the output can be positioned anywhere between 158?conduction angle for maximum brightness and 41? conduction angle for minimum brightness in relation to the ac line frequency. the positioning of the output is con- trolled by applying a low level at the sens input or a high level at the ext input. these functions may be implemented with very few inter- face components, as shown in figure 5. when imple- mented in this manner, touching of the touch plate caus- es the lamp brightness to change as follows: 1. if the touch plate is touched momentarily (42ms to 333ms), the lamp is: a) turned off if it was on, b) turned on if it was off. the brightness resulting is either full brightness or depending on the circuit type, a previous brightness stored in the ic memory. 2. if the touch plate is touched for a prolonged time (more than 342ms) the light intensity changes slowly. as long as the touch is maintained, the change con- tinues; the direction of change reverses whenever the maximum or minimum brightness is reached. lsi 1 2 3 4 8 7 6 5 trig v dd (-v) ext sens v ss (+v) doze cap sync ls7231-34 figure 1 pin assignment - top view the ic also provides an input for slow dimming. by applying a slow clock to this input, the lamp can be dimmed slowly until total turn off occurs. this fea- ture can be useful at bedtime in a child? room. input/output description: v ss (pin 1) supply voltage positive terminal. doze (pin 2) a clock applied to this input causes the brightness to de- crease in equal increments with each negative transition of the clock. eventually, when the lamp turns off, this in- put has no further effect. the lamp can be turned on again by activating either the sens input or the ext in- put. for the transition from maximum brightness to off, a total of 83 clock pulses are needed at the doze input. when either the sens or the ext input is active, the doze input is disabled. (see figure 7) cap (pin 3) the cap input is for the pll filter capacitor. a 0.047? capacitor should be connected to this input. 7231-4-120100-1 december 2000 features: phase-lock loop synchronization allows use in wall switch applications. provides brightness control of incandescent lamps with touch plates or mechanical switches. controls the "duty cycle" from 23% to 88% (conduction angles for ac half-cycles between 41? and 158?, respectively.) operates at 50hz/60hz line frequency. extension input for remote activation. input for slow dimming. +12v to +18v dc power supply voltage. (v ss - v dd ) ls7231 to ls7234 (dip) - see figure 1 ls7231-s to ls7234-s (soic) lsi/csi lsi computer systems, inc. 1235 walt whitman road, melville, ny 11747 (631) 271-0400 fax (631) 271-0405 LS7231-7234 u l a3800
table 1 touch type short (t s1 duration) long (t s2 duration) pre-touch post-touch pre-touch post-touch off max off starts varying at min max off max starts varying at max intermediate off intermediate starts varying at pre-touch brightness off memory off starts varying at (note 1) memory (note 2) max off max starts varying at max intermediate off intermediate starts varying at pre-touch brightness off max off starts varying at min max off max starts varying at max intermediate off intermediate starts varying at pre-touch brightness off memory off starts varying at (note 1) memory (note 2) max off max starts varying at max intermediate off intermediate starts varying at pre-touch brightness sync (pin 4) the ac line frequency is applied to this input through an external rc circuit (see figure 5). the phase-lock loop in the ic synchronizes all internal timings to the ac signal at the sync input. sens (pin 5) a low level activates this input (see table 1) which con- trols the turn-on, turn-off and conduction angle (see- figure 3) of the trig signal with respect to the sync in- put. ext (pin 6) the ext input is functionally identical to the sens input except that a high level activates this input. it is rec- ommended that the ext input be used instead of the sens input when long extension wires are employed be- tween the ic and the sensing circuitry (see figure 5 and figure 6) because the ext input is less susceptible to ?oise? v dd (pin 4) supply voltage negative terminal. trig (pin 8) the trig output is a low level pulse occurring once every half-cycle of the sync input. the conduction angle, , of the output in relation to the sync signal controls the lamp bright- ness. in continuous dimming operation (i.e. when the sens input is continuously held low) the trig conduction angle, , sweeps up and down between 41? and 158? continuously. the time vs curve is not linear (see figure 2). between two maxima on this curve, there are 4 discontinuous points labeled a1, b1, b2, a2. the discontinuities are as follows: 1. from maximum to a1. in this region, is changed by equal increments ( d ? for every 2 sync clocks. 2. from a1 to b1. in this region, the increments ( d ? take place for every 4 sync clocks. 3. from b1 to b2. in this region is held at a constant level ( d ?= 0). 4. from b2 to a2. same as 2. 5. from a2 to max. same as 1. the slower rate of change in ?over a1b1b2a2 region is to accommodate for eye adjustment at lower light intensity. the functional differences of different versions of the light dimmer ics are explained in table 1 and the trig output conduction angle diagrams in figure 2. part number ls7231 ls7232 ls7233 ls7234 dimming direction reversal (note 3) n/a n/a no yes n/a yes n/a n/a yes no n/a no note 1 : "memory" refers to the conduction angle, which existed prior to the current off-state. first time after power-up, the memory value defaults to maximum conduction angle. note 2: first time after power-up, long touch causes intensity to vary starting at minimum conduction angle. note 3 : no = dimming direction does not reverse from prior dimming direction. yes = dimming direction does reverse from prior dimming direction. n/a = does not apply 7231-34-033195-2
absolute maximum ratings: parameter symbol value unit dc supply voltage v ss +20 v any input voltage v in v ss -20 to v ss + 0.5 v operating temperature t a 0 to +80 ?c storage temperature t stg -65 to +150 ?c dc electrical characteristics: (t a = 25?c, all voltages referenced to v dd ) parameter symbol min typ max unit condition supply voltage v ss +12 +18 v - supply current i ss 1.0 1.4 ma v ss = +15v, output off input voltages: doze lo v izl 0 v ss -6 v - doze hi v izh v ss -2 v ss v - sync lo v irl 0 v ss -9.5 v - sync hi v irh v ss -5.5 v ss v - sens lo v iol 0 v ss -8 v - sens hi v ioh v ss -2 v ss v - ext lo v ivl 0 v ss -8 v - ext hi v ivh v ss -2 v ss v - input current: sync, sens, ext hi i ih 110 ? with series 1.5m w resistor to 115vac line sync, sens, ext lo i il 100 na - doze hi i ih 100 na - doze lo i il 100 na - trig hi voltage v oh v ss v - trig lo voltage v ol v ss -8 v v ss = +15v trig sink current i os 25 ma v ss = +15v v ol = v ss -4v timing characteristics (see figures 2 and 3): all timings are based on fs = 60hz, unless otherwise specified. 50hz timings are 1.2 times 60hz timings. parameter symbol min typ max unit sync frequency fs 40 - 70 hz short touch t s1 42 - 333 ms (on/off operation) long touch t s2 342 - infinite ms (dimming operation) doze frequency - - - 500 hz trig pulse width t w - 33 - ? trig conduction-angle 41 - 158 degrees (note 1) period (max to max in - - 7.64 - seconds continuous dimming) a1b1 = b2a2 duration - - 934 - ms b1b2 min. intensity dwell - - 500 - ms note 1 . in the circuit schematic shown in figure 5, the sync input signal is delayed in phase with respect to the ac line by about 7? this delay reduces the conduction angle, with respect to the ac line by 7?from the values shown above. 7231-34-041195-3
7231-4-032795-4 off 50 100 150 off 50 100 150 off 50 100 150 off 50 100 150 sens ls7231 ls7232 ls7233 ls7234 short long t s2 t s1 short 341ms long short long s aa s ba s aa s ba s aa s ba slope = s aa slope = s ba a 0 a1 a 1 a 2 a 2 b 2 b 2 b 1 b 2 b 1 memory reverse memory memory s ba = 1.4?per four sync cycles, 15 steps total for a 1 to b 1 or b 2 to a 2 s aa = 1.4?per two sync cycles, 68 steps total for a 0 to a 1 or a 2 to a 0 a 0 a 0 a 0 s aa s aa s aa s aa s aa s aa a 2 a 2 a 2 s ba s ba b 2 b 1 b 1 b 2 b 2 b 2 b 1 s ba s ba s aa s aa s ba s ba a 0 b 1 b 2 a 0 s aa a 1 a 1 a 2 a 1 b 2 memory figure 2. trig output conduction angle, , vs sens input
output driver digital comparator memory pointer phase lock loop control logic buf buf buf buf sync cap doze ext sens v ss v dd figure 4 ls7231-4 block diagram 4 3 2 6 5 1 7 trig (+v) (-v) 8 application example: a typical implementation of a lamp dimmer circuit is shown in fig. 5. here the brightness of the lamp is set by touch- ing the touch plate . the functions of different components are as follows: the 15v 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 c7 act as a filter circuit for the electronic extension. if extensions are not used, the ext input (pin 6) should be tied to v dd (pin 7). r4, r5, r6 set up the sensitivity of the sens input. c6 provides noise filtering. 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 rf filter circuits. in the case of momentary power failure, the circuit state remains unchanged for a period of up to 1 sec. for longer power interruptions, the output is shut off. trig sync t w t w figure 3. trig output conduction angle, 7231-4 040695-5
c1 = 0.15?,200v r4 = 1m w to 5m w ,1/4w c2 = 0.33?,200v (select for sensitivity) c3 = 0.047?,25v r5, r6 = 2.7m w ,1/4w c4 = 470pf,25v r7 = 150k w ,1/4w c5 = 47?,25v r8 = 100 w ,1/4w c6 = 680pf,25v d1 = in4148 c7 = 0.1?,25v z = 15v,1w (zener) r1 = 270 w ,1w t = q4006l4 triac (typical) r2 = 1.5m w ,1/4w l = 100? (rfi filter) r3 = 1.5m w ,1/4w (1) for connection a. use 0.22? for connection b. (2) for connection a. use 1/4w for connection b. c1 = 0.15?, 400v r4 = 1m w to 5m w ,1/4w c2 = 0.22?, 400v (select for sensitivity) c3 = 0.047?, 25v r5, r6 = 4.7m w ,1/4w c4 = 470pf, 25v r7 = 150k w ,1/4w c5 = 47?, 25v r8 = 100 w ,1/4w c6 = 680pf,25v d1 = 1n4148 c7 = 0.1?, 25v z = 15v,1w (zener) r1 = 1k w , 2w t = q5004l4 triac (typical) r2 = 1.5m w ,1/4w l = 200? (rfi filter) r3 = 1.5m w ,1/4w (3) for connection a. use 0.1? for connection b. (4) for connection a. use 1/4w for connection b. p 115vac or 220vac n load c1 t l c2 r1 r2 a b r8 r3 c5 d1 1 2 3 4 8 7 6 5 r4 c3 c4 trig v dd ext sens v ss doze cap sync + see note 4 ls7231-4 doze circuit (fig. 7) v ss dz sens v dd r6 r5 see note 3 figure 5. a typical lamp dimmer g z - electronic extension (fig. 6) extn p c7 see note 5 see note 2 r7 c6 notes 1) all circuits connected by broken lines are optional. 2) c7 is used only with electronic extension and r7 is used only with mechanical switch. 3) connection between pin 1 & pin 2 should be broken when doze circuit is used. 4) use connection a when neutral is not available. use connection b when neutral is available. 5) connection between pin 6 & pin 7 should be broken when ext is used. touch plate mt2 mt1 (1) 115v 220v 7231-4-041597-6 (2) (3) (4)
extn 2k w ,1/4w in914 touch plate *r 200k w ,1/4w mps8599 figure 6. electronic extension *r p *r = 2m w ,1/4w for 115vac *r = 3.6m w ,1/4w for 220vac vss vdd doze switch figure 7. doze circuit 3.3m ,1/4w + - 3.3m ,1/4w 10? sens dz u1-1 u1-2 u1-3 dz u1 = cd4093 extensions: all switching and dimming functions can also be implemented by utilizing the ext input. this can be done by either a mechanical switch 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) doze circuit: the doze circuit shown in figure 7 generates a slow clock (0.04hz) at the dz terminal. if the touch plate (figure 5) is not touched, the sens terminal of the doze circuit of figure 7 sits at a logic high level. a mo- mentary pressing of the doze switch sets the sr flip-flop, enabling the oscillator. every negative transition of the clock (dz terminal) causes the light intensity to be reduced by equal increments, until eventually the light is shut off. the oscillator has no further effect on the dimmer circuit. when the light is turned on again by touching thetouch plate, the sr flip-flop is reset and the dz clock is turned off. when the doze circuit is used, the connection between doze input (pin 2) and v ss (pin 1) as shown in figure 5, should be removed. . 7231-4-041195-7
115vac or 220vac c1 t1 l c2 r1 r2 r3 c5 d1 1 2 3 4 8 7 6 5 c3 c4 trig v dd ext sens v ss doze cap sync + ls7231-4 g mt2 mt1 z1 - r4 out to lamp ac on-off switch pushbutton switch figure 8. a switch-operated lamp dimmer (see note ) note: operation is independent of line plug polarity c1 = 0.15?, 200v c1 = 0.15?, 400v c2 = 0.22?, 200v c2 = 0.1?, 400v c3 = 0.047?, 25v c3 = 0.047?, 25v c4 = 470pf, 25v c4 = 470pf, 25v c5 = 47?, 25v c5 = 47?, 25v r1 = 270 w , 1/4w r1 = 1k w , 1/4w r2 = 1.5m w , 1/4w r2 = 1.5m w , 1/4w r3 = 100 w , 1/4w r3 = 100 w , 1/4w r4 = 1m w , 1/4w r4 = 1m w , 1/4w d1 = in4148 d1 = in4148 z1 = 15v, 1w (zener) z1 = 15v, 1w (zener) t1 = q4008l4 (typical) t1 = q5004l4 (typical) l = 100? (rfi filter) l = 200? (rfi filter) 115v 220v 7231-4-032995-8 applications: 1. foot-switch dimmer for large floor lamps. 2. hand-switch dimmer for end-table lamps. 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.
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