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LSI/CSI
UL
(R)
LS7237
(631) 271-0400 FAX (631) 271-0405
April 1995
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
A3800
TOUCH CONTROL LAMP STEP DIMMER
FEATURES: * PLL synchronization allows use as a Wall Switch * Provides brightness control of an incandescent lamp with a touch plate or mechanical switch * Can control speed of shaded pole and universal AC motors * Controls the "duty cycle" from 23% to 88% (conduction angles for AC half-cycles between 45 and 158, respectively) * Operates at 50Hz/60Hz line frequency * Extension input for remote activation * +12V to +18V DC Power Supply (VSS - VDD) * 8-Pin Plastic DIP , 8-Pin SOIC-See Figure 1
PIN ASSIGNMENT - TOP VIEW
V SS (+V)
1
8
TRIG
LSI
MODE
2
7
V DD (-V)
LS7237
CAP
3
6
EXT
DESCRIPTION: LS7237 is a monolithic, MOS integrated circuit designed to control the brightness of an incandescent lamp. The output of the LS7237 triggers a triac connected in series with a lamp(See Figure 5). The lamp brightness is determined by controlling the output conduction angle (triac triggering angle) in relation to the AC line frequency (See Figure 2). The output conduction angle can be varied by applying a low level pulse at the SENS input or a high level pulse at the EXT input. When implemented as shown in Figure 5, this is accomplished by touching the Touch Plate which causes the lamp brightness to change in specified steps as follows: LEVEL Off Night Light Mood Light Medium Maximum BRIGHTNESS (% Rated Wattage) 0 9 29 66 99
SYNC
4
5
SENS
FIGURE 1
INPUT/OUTPUT DESCRIPTION: VSS (Pin 1) Supply voltage positive terminal. MODE (Pin 2) The operating mode for the circuit is selected by connecting this input as follows: MODE INPUT VSS VDD Float SELECTED MODE Mode 0 Mode 1 Mode 2
The LS7237 can operate in one of three different modes selected by the MODE input. The Brightness Sequences produced by the different modes are as follows: MODE 0 1 2 BRIGHTNESS SEQUENCE Off-Max-Off Off-Mood-Med-Max-Off Off-Night-Mood-Med-Max-Off
CAP (Pin 3) PLL filter input capacitor. A 0.047F capacitor should be connected to this input. 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 pulse applied to this input causes the TRIG output to step to the next conduction angle in the sequence selected by the MODE input. The change in conduction angle takes place with the trailing edge of the SENS input pulse.
After AC power-up, the output comes up in the OFF state. Following that, every time the Touch Plate is touched, the output steps to the next level of brightness. The next step following the maximum brightness is the OFF state, initiating a new sequence.
7237-041100-1
EXT (Pin 6) CONDUCTION ANGLE, O The EXT input is functionally similar to the SENS input with No output the exception that a high-level pulse is the active signal. It is 45 recommended that the EXT input be used instead of the 70 SENS input when long extension wires are used between the 105 IC and the sensing circuitry (See Figure 5 and Figure 6) be158 cause the EXT input is less susceptible to "Noise". VDD (Pin 7) Supply voltage negative terminal. TRIG (Pin 8) The TRIG output is a low-level pulse of fixed duration occurring once every half-cycle of the SYNC input. The conduction angle, O of the output in relation to the SYNC signal controls the lamp brightness. The 5 levels of brightness correspond to the 5 values of O as follows:
BRIGHTNESS LEVEL Off Night Light Mood Light Medium Maximum
NOTE: In the 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, O with respect to the AC Line by 7 from the values shown above. 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.
SYNC
o
TRIG
TW
TW
FIGURE 2. TRIG OUTPUT CONDUCTION ANGLE, O
TS1
SENS
158
158
158
O, MODE 0
OFF
OFF 158 105 70
OFF
70
O, MODE 1
OFF
OFF 158 105 70 45
O, MODE 2
OFF
OFF
FIGURE 3. TRIG OUTPUT CONDUCTION ANGLE, O, VS SENS INPUT
7237-041395-2
ABSOLUTE MAXIMUM RATINGS: PARAMETER SYMBOL DC Supply Voltage VSS Any Input Voltage VIN Operating Temperature TA Storage Temperature TSTG DC ELECTRICAL CHARACTERISTICS: (TA = 25C, all voltages referenced to VDD) PARAMETER Supply Voltage Supply Current Input Voltages: MODE LO MODE HI SYNC LO SYNC HI SENS LO SENS HI EXT LO EXT HI Input Current: SYNC, SENS, EXT HI SYMBOL VSS ISS
VALUE +20 VSS -20 to VSS +0.5 0 to +80 -65 to +150
UNIT V V C C
MIN +12 -
TYPE - 1.0
MAX +18 1.4
UNIT V mA
CONDITION VSS = +15V, output off -
VIZL VIZH VIRL VIRH VIOL VIOH VIVL VIVH
0 VSS-1.5 0 VSS-5.5 0 VSS-2 0 VSS-2
- - - - - - - -
VSS-9 VSS VSS-9.5 VSS VSS-8 VSS VSS-8 VSS
V V V V V V V V
IIH
-
-
110
A
SYNC, SENS, EXT LO TRIG HI Voltage TRIG LO Voltage TRIG Sink Current
IL VOH VOL IOS
- - - 25
- VSS VSS-8 -
100 - - -
nA V V mA
With Series 1.5M Resistor to 115VAC Line VSS = +15V VSS = +15V VOL = VSS-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 SYNC Frequency SENS/EXT Duration TRIG Pulse Width SYMBOL fs TS1 TW MIN 40 50 TYPE 33 MAX 70 Infinite UNIT Hz ms s
SYNC CAP
4 3 2
BUF
PHASE LOCK LOOP
O MEMORY
MODE
BUF
DIGITAL COMPARATOR
OUTPUT DRIVER
8
TRIG
EXT
6
BUF
CONTROL LOGIC
O POINTER
SENS
5 1 7
BUF
VSS VDD
7237-041395-3
(+V) (-V)
FIGURE 4 LS7237 BLOCK DIAGRAM
APPLICATION EXAMPLES: A typical implementation of a lamp dimmer circuit is shown in Fig. 5. Here the brightness of the lamp is set by touching the Touch Plate . The functions of different components are as follows:
EXTN
TOUCH PLATE *R 2K ,1/4W IN914 MPS8599 *R *R 200K ,1/4W *R
* The 15V DC supply for the chip is provided by Z, D1, R1, C2, 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 filter circuit for the electronic extension. If extensions are not used, the EXT input (Pin 6) should be tied to VDD (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 up to 1 sec. For longer power interruptions, the output is shut off.
= 2M , 1/4W for 115VAC = 3.6M , 1/4W for 220VAC
P
FIGURE 6. ELECTRONIC EXTENSION
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)
FIGURE 5. A Typical Lamp Dimmer
P G T Z D1 C2 8 7 6 5 TRIG VDD EXT SENS LS7237 R1 R2 A B LOAD SEE NOTE 3 VSS MODE CAP SYNC 1 2 3 4 C3 C4 C6 R4 + C5 R8 SEE NOTE 2 C7 R3 R7 EXTN
P
MT1 MT2
SEE NOTE 4 115VAC OR 220VAC L C1 R6 R5
ELECTRONIC EXTENSION (FIG. 6) TOUCH PLATE
N 1) 2) 3) 4)
NOTES: All circuits connected by broken lines are optional. C7 is used only with electronic extension and R7 is used only with mechanical switch Use Connection A when Neutral is not available. Use Connection B when Neutral is available. Connection between Pin 6 and Pin 7 should be broken when EXT is used.
C1 = 0.15F,200V (1) C2 = 0.33F,200V C3 = 0.047F,25V C4 = 470pF,25V C5 = 47F,25V C6 = 680pF,25V C7 = 0.1F,25V (2) R1 = 270,1W R2 = 1.5M,1/4W R3 = 1.5M,1/4W
115V
R4 = 1M to 5M,1/4W (Select for sensitivity) R5, R6 = 2.7M,1/4W R7 = 150K,1/4W R8 = 100,1/4W D1 = IN4148 Z = 15V,1W (Zener) T = Q4006L4 Triac (Typical) L = 100H (RFI Filter)
C1 = 0.15F,400V (3) C2 = 0.22F,400V C3 = 0.047F,25V C4 = 470pF,25V C5 = 47F,25V C6 = 680pF,25V C7 = 0.1F,25V (4) R1 = 1K, 2W R2 = 1.5M,1/4W R3 = 1.5M,1/4W
220V
R4 = 1M to 5M,1/4W (Select for sensitivity) R5, R6 = 4.7M,1/4W R7 = 150K,1/4W R8 = 100,1/4W D1 = 1N4148 Z = 15V,1W (Zener) T = Q5004L4 Triac (Typical) L = 200H (RFI Filter)
(1) For Connection A. Use 0.22F for Connection B. (2) For Connection A, Modes 1 and 2. Use 1/4W for Mode 0 and Connection B, all Modes.
7237-041597-4
(3) For Connection A. Use 0.1F for Connection B. (4) For Connection A, Modes 1 and 2. Use 1/4W for Mode 0 and Connection B, all Modes.

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