LSI LS7237

LSI/CSI
UL
®
LS7237
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
(631) 271-0400 FAX (631) 271-0405
A3800
April 1995
TOUCH CONTROL LAMP STEP DIMMER
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
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
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
V SS (+V)
1
MODE
2
CAP
3
SYNC
4
LS7237
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).
PIN ASSIGNMENT - TOP VIEW
LSI
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
8
TRIG
7
V DD (-V)
6
EXT
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
CAP (Pin 3)
PLL filter input capacitor. A 0.047µF 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.
EXT (Pin 6)
CONDUCTION ANGLE, Ø
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”.
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, Ø with respect to the
AC Line by 7° from the values shown above.
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, Ø of the output in relation to the SYNC signal
controls the lamp brightness. The 5 levels of brightness correspond to the 5 values of Ø as follows:
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
ø
TRIG
TW
TW
FIGURE 2. TRIG OUTPUT CONDUCTION ANGLE, Ø
TS1
SENS
158˚
Ø, MODE 0
OFF
158˚
OFF
158˚
OFF
158˚
105˚
70˚
Ø, MODE 1
70˚
OFF
OFF
158˚
105˚
70˚
45˚
Ø, MODE 2
OFF
OFF
FIGURE 3. TRIG OUTPUT CONDUCTION ANGLE, Ø, 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
VALUE
+20
VSS -20 to VSS +0.5
0 to +80
-65 to +150
UNIT
V
V
˚C
˚C
DC ELECTRICAL CHARACTERISTICS:
(TA = 25˚C, all voltages referenced to VDD)
PARAMETER
Supply Voltage
Supply Current
SYMBOL
VSS
ISS
MIN
+12
–
TYPE
–
1.0
Input Voltages:
MODE LO
MODE HI
SYNC LO
SYNC HI
SENS LO
SENS HI
EXT LO
EXT HI
VIZL
VIZH
VIRL
VIRH
VIOL
VIOH
VIVL
VIVH
0
VSS-1.5
0
VSS-5.5
0
VSS-2
0
VSS-2
–
–
–
–
–
–
–
–
Input Current:
SYNC, SENS, EXT HI
IIH
–
SYNC, SENS, EXT LO
IL
TRIG HI Voltage
TRIG LO Voltage
TRIG Sink Current
VOH
VOL
IOS
MAX
+18
1.4
UNIT
V
mA
CONDITION
VSS = +15V,
output off
VSS-9
VSS
VSS-9.5
VSS
VSS-8
VSS
VSS-8
VSS
V
V
V
V
V
V
V
V
-
–
110
µA
–
–
100
nA
–
–
25
VSS
VSS-8
–
–
–
–
V
V
mA
With Series 1.5MΩ
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
SYMBOL
fs
TS1
MIN
40
50
TRIG Pulse Width
TW
-
SYNC
CAP
MODE
7237-041395-3
4
BUF
PHASE
LOCK
LOOP
3
2
BUF
EXT
6
BUF
SENS
5
BUF
VSS
1
(+V)
VDD
7
(-V)
TYPE
33
MAX
70
Infinite
-
UNIT
Hz
ms
µs
Ø
MEMORY
DIGITAL
COMPARATOR
CONTROL
LOGIC
Ø
POINTER
FIGURE 4
LS7237 BLOCK DIAGRAM
OUTPUT
DRIVER
8
TRIG
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:
TOUCH PLATE
*R
2KΩ ,1/4W
EXTN
• 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.
*R
IN914
MPS8599
*R
*R
= 2MΩ , 1/4W for 115VAC
= 3.6MΩ , 1/4W for 220VAC
200K Ω ,1/4W
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
P
SEE NOTE 2
MT2
C7
R8
G
MT1
T
Z
R7
EXTN
R3
+
C5
-
ELECTRONIC
EXTENSION
(FIG. 6)
SEE NOTE 4
D1
L
115VAC
OR
220VAC
R6
C1
8
7
6
5
TRIG VDD EXT SENS
C2
R5
TOUCH
PLATE
LS7237
R1
R2
VSS MODE CAP SYNC
1
2
3
4
A
C3
C4
B
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 = 0.15µF,200V
(1) C2 = 0.33µF,200V
C3 = 0.047µF,25V
C4 = 470pF,25V
C5 = 47µF,25V
C6 = 680pF,25V
C7 = 0.1µF,25V
(2) R1 = 270Ω,1W
R2 = 1.5MΩ,1/4W
R3 = 1.5MΩ,1/4W
115V
R4 = 1MΩ to 5MΩ,1/4W
(Select for sensitivity)
R5, R6 = 2.7MΩ,1/4W
R7 = 150KΩ,1/4W
R8 = 100Ω,1/4W
D1 = IN4148
Z = 15V,1W (Zener)
T = Q4006L4 Triac (Typical)
L = 100µH (RFI Filter)
(1) For Connection A. Use 0.22µF 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
R4
SEE NOTE 3
LOAD
N
C6
C1 = 0.15µF,400V
(3) C2 = 0.22µF,400V
C3 = 0.047µF,25V
C4 = 470pF,25V
C5 = 47µF,25V
C6 = 680pF,25V
C7 = 0.1µF,25V
(4) R1 = 1KΩ, 2W
R2 = 1.5MΩ,1/4W
R3 = 1.5MΩ,1/4W
220V
R4 = 1MΩ to 5MΩ,1/4W
(Select for sensitivity)
R5, R6 = 4.7MΩ,1/4W
R7 = 150KΩ,1/4W
R8 = 100Ω,1/4W
D1 = 1N4148
Z = 15V,1W (Zener)
T = Q5004L4 Triac (Typical)
L = 200µH (RFI Filter)
(3) For Connection A. Use 0.1µF for Connection B.
(4) For Connection A, Modes 1 and 2. Use 1/4W for Mode 0
and Connection B, all Modes.