proximity/touch control halogen lamp dimmer description: ls7232nt is a cmos integrated circuit designed for brightness control of incandescent lamps or tranformer coupled low voltage halogen lamps. the brightness is controlled by controlling the fir- ing angle of a triac in series with the lamp and triggered by the ls7232nt. a phase-locked-loop keeps the ls7232nt phase pointer locked in phase with the line voltage. a unique optical user interface provides for a smooth control of the lamp intensity without the need for touching any sensor plate. a mechanical switch interface for dimming control is also provided which can be used for a remote touch plate. the ic in- cludes features to address problems associated with inductive loads such as transformers in low voltage halogen lamp applica- tion. the voltage to current phase lag resulting from the in- ductance may prevent the triac from shutting off at ac zero crossover and/or prevent the triac from maintaining conduction following the removal of the gate trigger. the inductive load problems are addressed by the ls7232nt as follows: 1. compensation for delayed triac cut-off. when 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 elim- inates 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? (60hz) is issued by the dimmer ic. if the triac fails to fire, a second trigger pulse of 260.4? width is issued 1 ms 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 the delayed turn-on exceeds a preset threshold, a shut- down 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 oc- currence of delayed cut-off or delayed turn-on and decre- ments once every 8 sync pulses (ac line cycles). the count will not decrement below zero. if the count reaches 15, the safety-shut-down is effected. pin assignment - top view 1 2 3 4 5 6 7 8 9 10 11 12 13 14 ls7232nt cap sync anode cathode photout sens remote v dd (+v) m2 m1 rc ledo trig/ vss (-v) figure 1 the ls7232nt can be configured in 7 different modes of dim- ming and timing off functions selected by two 3-state mode pins. input/output description: cap (pin 1) pll filter capacitor input. a 0.02? capacitor is required at this input for the optimal operation of the pll. sync (pin 2) the phase pointer for the triac trigger signal is synchronized with the 50hz/60hz ac voltage applied at the sync input by the internal pll. the triac on/off status information is also de- rived from this input. anode (pin 3) cathode (pin 4) and photout (pin 5) these three pins constitute the input/outputs of a trans- conductance and voltage amplifier pair (see fig. 6) for con- verting the current from a photo-diode to a voltage stimulus for application at the sens input. the photo-signal is used in lieu of a touch plate for a touchless dimmer system. the output at photout is governed by the following equation: v out = v dd /2 + 2i d r f where v dd = supply voltage i d = current in photo-diode connected between anode and cathode r f = feedback resistance between photout and cathode a potentiometer is used for r f for controlling the sensitivity of the photo-amplifier system. 7232nt-042005-1 april 2005 features: ?control of incandescent and transformer-coupled low voltage halogen lamps. ?no-touch lamp control through optical sensing ?pll synchronization of ac for wall switch application. ?extension input for remote control ?safety-shutdown for transformer malfunction. ?pin-selectable operating modes ?single 5v power supply ?50hz/60hz ac line frequency ?ls7232nt (dip); ls7232nt-s (soic) - see figure 1 lsi/csi lsi computer systems, inc. 1235 walt whitman road, melville, ny 11747 (631) 271-0400 fax (631) 271-0405 ls7232nt u l a3800
sens (pin 6) a positive signal applied at the sens input controls the turn-on, turn-off and dimming function of the ls7232nt. the sens in- put is designed to operate with very low levels of signal, so that it can be directly interfaced with the photoamplifier output. sig- nal at the sens input is amplified with a gain of 30. if a photo- sensor is not to be used, the sens input can easily be adapted to a touch plate. signals at the sens input are classified as short touch and long touch. signals between 50ms and 350ms constitute a short touch, whereas signals longer than 350ms constitute a long touch. the functions of these two types of touches are explained in the mode description section. sens input has an internal pull-down resistor of 10k w . remote (pin 7) for performing dimming operation from remote sites or through wire extensions, the remote input is used. this input is sam- pled twice during both negative and positive half cycles of the ac, rendering it more immune to noise and hence more suited for carrying signals over extension wires. vss ( pin 8) supply voltage, negative terminal . t rig/ (pin 9) trigger ouput for driving the gate of a triac. a negative pulse of nominally 130.2s duration is generated at this output which can be varied between 19.7? and 119.5? from the zero- crossover of the ac during every half cycle. the control of con- duction angle of the trig/ output is effected by short and long touches at the sense and remote inputs. ledo (pin 10) a positive pulse of 32s is generated at this output during every negative half-cycle of the ac. if the trig/ output is off, the ledo is generated nominally 911s after the ac zero- crossover in the negative half-cycles. if the trig/ output is on, the ledo tracks the trig/ output signal and is generated 170s ahead of the trig/ output, during every negative half- cycle of the ac. the ledo is used to drive an infra-red led. when a reflecting object, such as a human hand, is brought close to the infrared led, the light is reflected back to the photo-diode, which is mounted in physical proximity to the infra-red led. the change of intensity of the received light by the photo-diode results in a change of the photo-diode current which in turn is amplified by the transconductance amplifier as described in the anode input section. rc (pin 11) a resistor-capacitor pair connected externally to the rc input constitutes the timing element for the delay generation in modes 4, 5, 6, and 7. the delay is given by the expression, d = 63rc. m1 and m2 (pin 12 and pin 13) each of these inputs are 3-state inputs, namely low (l), high (h) and float (f). the logic levels of these two inputs together, configures the operating modes of the ls7232nt according to table 1. mode descriptions: see figures 2, 3, and 4 for further explanations. mode 1 - touch causes the trig/ output to toggle between off and max. the off to max transition slews in 350ms(tr). long and short touch operate in identical manner. leading edge touch sense (change occurs upon initiation of touch) 7232nt-012703-2 table 1. operating modes m1 m2 mode description l l 1 on - off l f 2 on - off - dimmer l h 3 on - off - memory - dimmer f f 4 on - delayed_off - dimmer f h 5 on - delayed_off - memory-dimmer f l 6 on - delayed_off h l 7 on - auto_off_timer h f x not allowed h h x not allowed mode 2 - same effect for short touch as in mode 1. long touch causes the output to sweep between conduction angles of 38? (min) and 155? (max) in increments of 1.4?. the sweep direction auto- matically reverses at min and max. sweep direction also reverses for every long touch. trailing edge sensing for short touch. (change occurs upon removal of touch.) mode 3 - same as mode 2 except for short touch the output toggles between off and memory. memory is updated with the long touch. mode 4 - same as mode 2 except the on to off operation with short touch is delayed. at the termination of the short touch the out- put level instantaneously drops by an amount of d to indicate the beginning of the turn-off delay, t rc . at the end of the delay, the output slews off at a rate of 56?/s. the delay t rc is controlled by a resistor- capacitor pair at the rc (pin 11) input, according to the following expression: t rc = 63rc the magnitude of d is dependent on the pre-touch intensity from where the turn-off delay is initiated and can have one of the values in table 2 (see fig. 2 and 3). mode 5 - same as mode 4, except a short touch in the off state switches the output to memory. mode 6 - same as mode 4, except that there is no dimming func- tion in mode 6. both short and long touches operate as short touch (leading edge touch sense). mode 7 - output switches from off to max with either short or long touch (leading edge touch sense). after a delay of t rc = 63rc (see description of mode 4) the output drops by an angle d according to table 2. after another fixed delay of 10sec (t f ) the output slews off in 2sec (t d7 ) at the rate of 56?/sec. a touch during t rc time out has no effect. a touch during t f and t d7 timeouts aborts the timeout and restores output to max. table 2. brightness drop at delay start, d pre-touch conduction angle 155? to 130? -35? 129? to 115? -25? 114? to 95? -20? 94? to 45? -10? 44? to 38? instantaneous off
absolute maximum ratings: parameter symbol value unit dc supply voltage v dd - v ss +7 v any input voltage v in vss - 0.3 to v dd + 0.3 v operating temperature t a 0 to +90 ?c storage temperature t stg -65 to +150 ?c 7232nt-012703-3 dc electrical characteristics: (t a = 25?c, v dd = +5v, all voltages referenced to vss) parameter symbol min typ max unit condition supply voltage v dd 4.5 5.0 5.5 v - supply current i dd e 400 500 a output unloaded input logic levels: sync lo - - e 2.0 v - sync hi - 3.0 e - v - remote lo - - e 1.5 v - remote hi - 3.5 e - v - sens lo - - e 50 mv - sens hi - 150 e - mv - rc lo - - - 2.0 v - rc hi - 3.0 - - v - output current: ledo sink - -1.0 -1.5 - ma vo = 0.5v ledo source - 10.0 14.0 - ma vo = 2.2v trig/ sink - -35.0 - - ma vo = 3.5v rc sink - -3.0 -4.0 - ma vo = 2.0v transient characteristics (see figures 2, 3, 4 and 5): all time parameters are based on 60hz sync. for 50hz a multiplication factor of 1.2 should be used. parameter symbol min typ max unit condition sync frequency fs 40 - 70 hz - short touch ts 50 - 350 ms - long touch t l 350 - infinite ms - trig/ pulse width t w - 130.2 - s - conduction range 38 - 155 deg - increments s - 1.4 - deg = 84 s short touch: off to max (slew time) t 1 - 350 - ms - long touch: ramp time between 38? & 59? t 2 - 1.0 - sec - ramp time between 59? & 155? t 3 - 2.27 - sec - dwell at min t 4 - 500 - ms -
parameter symbol min typ max unit condition timer resistor r 200 - 2m ohm - timer capacitor c 0.1 10.0 - f - timer delay t rc 1e - 3 - 1200 sec t rc ? 63rc slew off rate t sf - 42 - deg/sec 60hz - 35 - deg/sec 50hz slew off delay t d - d/tsf - sec - pre-off delay (mode 7) t f - 10 - sec - slew-off delay (mode 7) t d7 - 2 - sec - ledo pulse width - - 32 - s - sync to ledo delay t sl - 918 - s - ledo to trig/ delay t tl - 170 - s - ledo to strobe delay t b - 24 - s - 7232nt-012703-4 sync (idealized) trig/ ledo sens_strobe (internal) t sl t tl t w p1 p2 p1 p2 t b note: pulse p1 and its associated sens_strobe occurs only when the trig/ is off pulse p2 and its associated sens_strobe occurs only when the trig/ is on. figure 2. trig/ conduction angle, definition and ledo pulse 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.
155 59 38 off mode 1 mode 3 figure 3. modes 1, 2 and 3 t l t s t 1 t 4 t 2 t 3 short long short short short short long long no memory memory sens long 155 59 38 off mode 2 155 59 38 off
trigger logic digital comparator pointer phase lock loop control buf buf sync cap amp gain=30 photout sens v ss v dd figure 6. ls7232nt block diagram 1 2 13 6 8 14 trig/ 9 4 3 7 12 5 phase memory triac status driver driver cathode anode remote 11 decoder amp amp timer 10 ir pulse logic m1 m2 rc ledo 10k +v -v 7232nt-012703-6 amp + - amp + - 5 4 3 100k r f 100k v dd /2 id figure 7 . photo amplifier with photo diode and gain resistor , r f anode cathode photout (v out ) v out = v dd /2 + 2i d r f
p 115vac or 220vac n load c1 t l c4 r1 r2 r r6 c5 d1 1 2 3 4 8 7 6 5 c3 c7 v dd v ss ls7232nt g z r5 notes 1) for a no-touch system, the infra-red transmit diode d3 and and receive d2 should be placed in physical proximity so that when a hand is placed in front of d2 and d3, reflected light from the hand is received by the ir receiver d3 to produce a touch impulse. 2) if a touchplate is used the following parts should be in: r8, r9, c8 and p1. if infrared detector is used the following parts should be in: d2, d3, r4, r5, r6, c7 and n1. 3) if remote sensing is not used the following parts may be removed: r3, r10, r11, r12, r13, c6 and p2. if remote sensing is used these parts should be in and the connection between pin 7 and pin 8 must be broken. 4) the load is either an incandescent lamp or the primary of a step-down transformer for a low voltage halogen lamp. r9 r8 touch plate mt2 mt1 c2 9 10 11 12 13 14 r4 r3 rc anode cathode photout m1 m2 sync cap ledo sens remote trig/ r11 r10 touch plate c c8 c6 r13 r14 p1 d4 p2 n1 r7 d3 p figure 8. a typical dimmer circuit with no-touch optical sensing and touch plate options r12 see note 3 d2 c = 0.1f to 10f, 10v r = 200 w to 2m w , 1/4w c1 = 0.15f, 200v r7 = 51 w , 1/4w c2 = 0.22f, 200v r8, r9 = 2.7m w , 1/4w c3 = 0.02f, 10v r10, r11 = 2.7m w , 1/4w c4 = 0.002f, 10v r12 = 200k w , 1/4w c5 = 200f, 10v r13 = 2k w , 1/4w c6 = 0.1f, 10v r14 = 1 to 5m w , 1/4w c7 = 0.003f, 10v d1 = in4148 c8 = 0.1f, 10v d2 = sfh205, ir receiver diode r1 = 270 w , 1/2w d3 = ld271, ir transmitter diode r2 = 680k w , 1/4w d4 = in4148 r3 = 1.5m w , 1/4w z1 = 5.6v, 1w (zener) r4 = 500k w , 1/8w pot. t1 = q2004l4 triac (typical) r5 = 51 w , 1/4w l = 100f, rfi filter r6 = 1k w , 1/4w n1 = mps8099, npn p1, p2 = mps8599 (1) all components are the same as 115v except as listed below: c1 = 0.15f, 400v c2 = 0.22f, 400v r1 = 1k w , 1w r2 = 1.5m w , 1/4w r8, r9 = 4.7m w , 1/4w t1 = q4004l4 triac (typical) l = 200f, rfi filter 115v 220v (1) 7232nt-042005-7
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