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LSI/CSI
UL
(R)
LS7338
(631) 271-0400 FAX (631) 271-0405
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
A3800
DELAYED-OFF LIGHT SWITCH WITH PROGRAMMABLE ON-TIMER
FEATURES: * Phase-Lock Loop Synchronization allows use in Wall Switch Applications. * Operation automatically sequences from Timed-On to Delayed-Off to Off. * On-Timer programmable with external R-C. * Transition from Timed-On to Delayed Off indicated by 31% drop in Delivered Power. * Delayed-Off period denoted by Dim-to-Off operation. (See Note 1) * Control input initiates Operating Sequence and can override Automatic Sequencing. * 50/60Hz Line Frequency. * +12V to +18V Operation (VSS - VDD). * LS7338 (DIP); LS7338-S (SOIC) - See Figure 1 NOTE 1: Dim-to-Off time is Mask Programmable. The standard IC is fixed at 209 seconds for 60Hz. Dim-to-Off time can be programmed within a range of 6.5 to 836 seconds. APPLICATIONS: * WALL SWITCH for incandescent lighting in garage, corridor, staircase, child's bedroom, teenage study area. * IN-LINE SWITCH for table lamps. DESCRIPTION: The LS7338 is a monolithic MOS integrated circuit designed to turn a triac On and Off in a Power Switch for Incandescent Lighting. Activation of SENSE or SLAVE inputs turns the triac On and starts a timer. The triac remains On for the duration of the Timer which is controlled by an external R-C connected to the OSCILLATOR input. When Time-out occurs, the power delivered by the triac is stepped down by 31% and then slowly reduced to Off over a fixed period of time. In a typical application (Figure 5), the output of the LS7338 drives the gate of a triac in series with the load. There are three states through which the LS7338 can be stepped. The states and their corresponding operating mode, phase angles and delivered power levels are shown in Table 1. (See Figures 2 and 3) OPERATING MODE PHASE ANGLE, o % LOAD POWER (1) TABLE 1 STATE 0 STATE 1 OFF No Output 0 Timed-On 159 99 STATE 2 Delayed -Off 107 to 41 68 to 7
PIN ASSIGNMENT - TOP VIEW
June 2001
SENSE
1
8
SYNC
LSI
SLAVE
2
7
CAP
LS7338
VDD (-V)
3
6
OSC
TRIG
4
5
VSS (+V)
FIGURE 1
OPERATING DESCRIPTION: Upon power up, internal power-on-reset starts the LS7338 in STATE 0. When the SENSE input transitions to logic 0, or the SLAVE input transitions to logic 1, the IC steps to STATE 1. When implemented as shown in the application example (Figure 5), this is accomplished by touching the appropriate Sensor Plate. Subsequent similar transitions at SENSE or SLAVE inputs cause the LS7338 to step through the sequence: STATE 0 --> STATE 1 --> STATE 2 --> STATE 0, etc. STATE 1 and STATE 2 are quasi-stable states. If left in STATE 1, after a time-out period determined by the frequency set at the OSC input (See I/O Description, Pin 6), the IC automatically steps to STATE 2. (If the OSC input is deactivated, STATE 1 becomes stable and its OPERATING MODE is denoted as On). When the IC steps from STATE 1 to STATE 2, the output phase angle o changes from 159 to 107. This corresponds to a delivered power reduction of 31%, which causes a reduction of lamp brightness. This brightness change provides the user with a positive indication that the transition from STATE 1 to STATE 2 has occurred. The Time-out period for STATE 2 is fixed at 209 seconds for 60Hz operation. (See Note 1.) TD1 = STATE 1 Time-out period. TD2 = STATE 2 Time-out period. During the STATE 2 Time-out, the TRIG phase angle o (See Figure 2) is ramped down from 107 to 41 in decrements of 1.4. When o reaches 41, the IC automatically steps to STATE 0, shutting the TRIG and lamp Off. The slow Dim-to-Off in STATE 2 gives the user a continuing reminder that Delayed-Off is operating and provides the time and light with which to leave the area or to recycle the Light Switch. A new operating sequence from STATE 0 can be started only by transitions at the SENSE and SLAVE inputs.
(1) The percentage of full power delivered to a resistive load by the triac switch.
7338-062001-1
INPUT/OUTPUT DESCRIPTION: SENSE (Pin 1) A logic 0 applied to this input for a minimum of three SYNC cycles, TS1 (50ms for 60Hz, 60ms for 50Hz), causes the circuit to step to the next state in the operating sequence. SLAVE (Pin 2) Same description as SENSE (Pin 1) except that logic 1 replaces logic 0. This input is designed to be used with Remote Extensions (See Figure 5 and Figure 6.) VDD (Pin 3) Supply voltage negative terminal. TRIG (Pin 4) TRIG is a negative-going pulse occurring once every half cycle of the SYNC input. Pulse width is 33s. Table 1 in the General Description shows values of the TRIG phase angle for the different states. (See Figure 2 and Figure 3.) ABSOLUTE MAXIMUM RATINGS: PARAMETER DC supply voltage Any input voltage Operating temperature Storage temperature SYMBOL VSS - VDD VIN TA TSTG
VSS (Pin 5) Supply voltage positive terminal. OSC (Pin 6) An R-C network connected to this input controls the frequency of oscillation which determines the Time-out, TD1, in State 1. TD1 is approximately 255RC. The Oscillator is active only in State 1. Chip to chip Oscillation Tolerance is 10% for fixed value of RC. Tie Pin 6 to VSS if a Time-out is not desired. (See Figure 5.) CAP (Pin 7) The CAP input is for external component connection for the PLL filter capacitor. (See Figure 5.) SYNC (Pin 8) The AC Line Frequency (50/60Hz) is applied to this input. The Phase-Lock Loop synchronizes all internal timings to the AC signal at the SYNC input. (See Figure 5.)
VALUE +20 VSS-20 to VSS + .5 0 to +85 -65 to +150
UNIT V V C C
DC ELECTRICAL CHARACTERISTICS: (TA = 25C, all voltages referenced to VDD) PARAMETER Supply Voltage Supply Current SYMBOL VSS ISS MIN +12 TYP 1.6 MAX +18 2.2 UNIT V mA CONDITIONS VSS = +15V, Output off
Input Voltages SYNC Lo SYNC Hi SENSE Lo SENSE Hi SLAVE Lo SLAVE Hi Input Current SYNC, SENSE & SLAVE Hi SYNC, SENSE & SLAVE Lo TRIG Hi Voltage TRIG Lo Voltage TRIG Sink Current
VIRL VIRH VIOL VIOH VIVL VIVH
0 VSS-5.5 0 VSS-2 0 VSS-2
-
VSS-9.5 VSS VSS-8 VSS VSS-8 VSS
V V V V V V
-
IIH
-
-
110
uA
With Series 1.5M Resistor to 115VAC
IIL VOH VOL IOS
25
VSS VSS-8 -
100 -
nA V V mA
VSS = +15V VSS = +15V,VOL = VSS -4V
TRANSIENT CHARACTERISTICS (See Fig. 2 and 3) (All timings are based on Fs = 60Hz, unless otherwise specified.) PARAMETER SYNC Frequency SENSE/SLAVE Sense Time TRIG Pulse Width STATE 1 Time-out period STATE 2 Time-out period SYMBOL Fs Ts1 Tw TD1 TD2 MIN 40 50 TYP 33 255RC 209 MAX 70 Infinite UNIT Hz ms s s s
7338-112497-2
SYNC
o
TRIG
Tw
Tw
FIGURE 2. OUTPUT CONDUCTION ANGLE, O
SENSE TS1 SLAVE TS1
TS1
O OFF/STATE 0
107/STATE 2 < 41/STATE 2 OFF/STATE 0
107/STATE 2 41/STATE 2 OFF/ STATE 0
FIGURE 3.
OUTPUT PHASE ANGLE
o VS
SENSE AND SLAVE
SYNC
8
BUF
PHASELOCK LOOP
SYNC PHASE-ANGLE POINTER DIGITAL COMPARATOR DRIVER 4 TRIG
CAP
7
SENSE
1
BUF
CONTROL LOGIC
o
DECODE
SLAVE
2
BUF
OSC V SS V DD
6
OSC/TIMER
5 3
(+V) (-V)
FIGURE 4.
LS7338 BLOCK DIAGRAM
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.
7338-112497-3
FIGURE 5. A TYPICAL LIGHT SWITCH APPLICATION
SEE NOTE 2 P
G MT1
P R10 EXTN
R6 + Z1
C7 R9
T1
MT2
-
C3 SEE NOTE 3 R4 4 R7 3 2 1 OUT V DD SLV S E N S E LS7338 V SS OSC CAP SYNC 5 6 7 8 C3 C4 R5 R3
ELECTRONIC EXTENSION (Figure 6)
AC MAINS
L1 C1
D1 C2
SENSOR PLATE
R1 R2 A B LOAD N SEE NOTE 1 R8 C6
+
NOTES:
1. Use Connection A when Neutral is not available. Use Connection B when Neutral is available. 2. C7 is used only with Electronic Extension. R10 is used only with Mechanical Switch. 3. Connection between Pin 2 and Pin 3 is removed when SLAVE input is used. 4. See Table 2 for Component Functional Description
(1) R1 (2) R1 R2 R3 R4 (3) R5 R6 R7 R8 R9 R10 C1
115VAC 270, 1W 82 1.5M 2.7M 2.7M 1M to 5M 100 (4) (4) 1.5M 150k 0.15F, 200V
220VAC 1k, 2W (1) 82 (2) 1.5M 4.7M 4.7M 1M to 5M 100 (4) (4) 1.5M 150k (6) 0.15F, 400V
C2 C2 C3 C4 C5 C6 C7 Z1 D1 L1 T1
115VAC 0.33F,200V 0.22F,200V 47F 470pF .047F (5) 0.1F,200V 15V, 1/2W 1N4148 100H Q4008L4
220VAC 0.22F,400V 0.1F,400V 47F 470pF .047F (5) 0.1F,400V 15V, 1/2W 1N4148 200H Q5004L4
TABLE 2 . FIGURE 5 COMPONENT FUNCTIONAL DESCRIPTION COMPONENTS Z1, D1, R1, C2, C3 R2, C4 C1, L1 C5 R3, R4, R5 FUNCTIONAL DESCRIPTION DC Power Supply. Current limit and filter AC for SYNC input. RFI filtering for AC Mains. PLL filter capacitor. Network sets the Touch Sensitivity for the SENSE input. Current limiting and isolation between IC output and Triac Gate. Oscillator R-C network. Potentiometer R6 required only if providing user adjustment of Time-out, TD1. Filter for the Electronic Extension Current limiting resistor for the Mechanical Switch Extension.
(1) Connection A (2) Connection B (3) Select for desired touch sensitivity (4) 100k (R7 + R8) 10M (5) (R7 + R8)C6 5ms (6) Typical All Resistors 1/4W, all Capacitors 25V unless otherwise specified
R6
R7, R8, C6
R9, C7 R10
SENSOR PLATE 2M ,1/4W
EXTN
2K ,1/4W IN914 MPS8599 2M ,1/4W
200K ,1/4W
P
FIGURE 6. ELECTRONIC SWITCH EXTENSION
EXTENSIONS: (See Figure 5 and Figure 6) All sequence functions can also be inplemented by utilizing the SLAVE input. This can be done by either a mechanical switch or the electronic switch in conjunction with a sensing plate as shown in Figure 6. When the plate is touched, a logic high level is generated at the EXTENSION terminal for both half cycles of the line frequency.

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