EXTENSIONS: All On / Off switching functions can be imple-

mented by utilizing the EXT input. Use a pushbutton 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)

APPLICATION EXAMPLE:

A typical implementation of the light dimmer circuit is shown in Fig. 5.

Here the lamp is turned on and off by touching the touch plate.

The function of different components are as follows:

• The 5V DC supply for the chip is provided by Z, D1, R1, C2 and C4.

• R2 and C3 generate the filtered signal for the SYNC input

AC phase synchronization.

• R3 and C5 act as a filter circuit for the electronic extension.

If extensions are not used, the EXT input (Pin 6) should be

tied to Vss (Pin 7).

• R4, R5 and R6 set up the sensitivity of the SENS/ input.

• R8 provides current limiting and isolation between the chip

output and the triac gate.

• C1 and L are RFI filter circuits.

• R10, R11, R12 and C7 selects and adjusts the dimming level.

C1 = 0.15µF, 200V

C1 = 0.15µF, 400V

C2 = 0.22µF, 200V

C2 = 0.15µF, 400V

C3 = 0.002µF, 10V

C4 = 100µF, 10V

C5 = 0.1µF, 10V

C6 = 0.01uF, 10V

C7 = 0.1uF, 10V

R1 = 270Ω, 1/2W

R1 = 1kΩ, 1W

R2 = 680kΩ, 1/4W

R2 = 1.5MΩ, 1/4W

R3 = 1.5MΩ, 1/4W

R4 = 1MΩ to 5MΩ, 1/4W

(Select for Sensitivity)

R5, R6 = 2.7MΩ, 1/4W

R5, R6 = 4.7MΩ, 1/4W

R7 = 150kΩ, 1/4W

R8 = 62Ω, 1/4W

R10 = 33kΩ, 1/4W

R11 = 100kΩ Pot., 1/4W

R12 = 16kΩ, 1/4W

D1 = 1N4148

Z = 5.6V, 1W (Zener)

T = Q4004L4 Typical Triac

(1)

T = Q5003L4 Typical Triac

(1)

L = 100µH (RFI Filter)

L = 200µH (RFI Filter)

(1) For loads greater than 6A,

use an alternistor

*

*

*

*

*

*

*

EXT

10kΩ

IN914

TOUCH PLATE

*R

200kΩ

MPS8599

FIGURE 6. ELECTRONIC EXTENSION

*R

P

*R

= 2MW for 115VAC

*R

= 3.6M W for 220VAC

All Resistors 1/4W

7642-101308-4

FIGURE 4. TRIG/ OUTPUT CONDUCTION ANGLE, Ø

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.

ø

TRIG/

SYNC

P

115VAC

OR

220VAC

N

LAMP

C1

T

L

C2

R1

R2

R8

R3

C4

D1

8

7

6

5

R4

C3

SYNC

+

LS7642

R6

R5

FIGURE 5. A Typical Halogen Lamp Dimmer Wall Switch

G

MT2

MT1

Z

-

ELECTRONIC

EXTENSION

(FIG. 7)

EXTN

P

C5

SEE NOTE 3

SEE NOTE 2

R7

NOTES

1. All circuits connected by broken lines are optional.

2. C5 is used only with electronic extension

and

R7 is used only with pushbutton switch.

3. Connection between Pin 6 & Pin 7 should

be broken when EXT is used.

4. Magnetic transformer should have thermal protection.

5. Some electronic transformers may require larger values

of

C2, sensitive gate triacs and snubber networks. C2

values may have to be adjusted to be as high as 0.47uF

for 115VAC and 0.33uF for 220VAC. Sensitive gate triacs

are chosen for their low holding current. Typical triacs are

L4004L6 and L4004F51 for 115VAC and L6004L6 and

L6004F51 for 220VAC applications, respectively.

**C6-R9 is the snubber network:

C6 = 0.1uF, 200V, R9 = 1k Ohm, 1/2W (115VAC);

C6 = 0.05uF, 400V, R9 = 1k Ohm, 1W (220VAC)

6. The values selected for R10, R11, and R12 will produce the

full dimming range. To reduce the maximum intensity,

increase the value of R12. To increase the minimum

intensity, increase the value of R10. Increasing either R10

or R12 will reduce the dimming range. R10 may have to be

increased for very low wattage loads.

TOUCH

PLATE

SEE

NOTE 4

TEST

1

2

3

4

**R9

**C6

C7

R10

R11

R12