DIMMER LIGHT SWITCH

WITH UP AND DOWN CONTROLS

FEATURES:

• Phase-lock loop synchronization allows use as a

Wall Switch

• Brightness control of incandescent lamps with touch

plates (LS7534) or mechanical switches (LS7535)

• Dual Controls eliminate confusion

• Soft turn-on /turn-off

• Controls the "Duty Cycle" from 23% to 88%

(conduction angles for AC half-cycles between 41°

and 159°, respectively)

• Operates at 50Hz/60Hz line frequency

• Input for slow dimming

• LS7534/LS7535 (DIP);

LS7534-S/LS7535-S SOIC - See Figure 1

DESCRIPTION:

LS7534/LS7535 are monolithic, MOS integrated cir-

cuits that are designed for brightness control of in-

candescent lamps. The outputs of these ICs control

the brightness of a lamp by controlling the firing an-

gle of a triac connected in series with the lamp. All

internal timings are synchronized with the line fre-

quency by means of a built-in phase-lock loop cir-

cuit. The output occurs once every half-cycle of the

line frequency. Within the half-cycle, the output can

be positioned anywhere between 159° conduction

angle for maximum brightness and 41° conduction

angle for minimum brightness in relation to the AC

line frequency. The positioning of the output is con-

trolled by applying the proper logic levels at the UP

and DOWN inputs.

These functions may be implemented with very few

interface components which is described in the ap-

plication examples (See Fig. 5A and 5B). For touch

plates, LS7534 is used (Fig. 5A). For mechanical

switches, LS7535 is used (Fig. 5B).

In the following Operating Description of the applica-

tion examples, an Activation is Touch for LS7534

and Switch Closure for LS7535.

Short Activation (34ms to 325ms)

UP - When the lamp is off, if a short activation is applied to

the UP input, the lamp brightness is ramped up to full-on or

to a previous brightness stored in the memory. The ramp-

up time from off to full-on is 2.8 sec. The ramp-up time from

off to any other brightness is proportionally shorter. When

the lamp is on at any brightness, a short activation applied

to the UP input has no effect.

DOWN - If a short activation is applied to the DOWN input,

the lamp brightness is ramped down to off. The ramp-down

time from full-on to off is 5.6 seconds. The ramp-down time

from any other brightness is proportionally shorter. When

the lamp is off, a short activation applied to the DOWN input

has no effect.

Long Activation (Greater than 334ms)

UP - If a long activation is applied to the UP input, the lamp

brightness ramps up from the pre-activation brightness as

long as the activation is maintained or until the full bright-

ness is reached. At full brightness any continued long ac-

tivation has no further effect.

DOWN - If a long activation is applied to the DOWN input,

the lamp brightness is ramped down as long as the long ac-

tivation is maintained or until the minimum brightness is

reached. At minimum brightness, any continued long ac-

tivation has no further effect. When the lamp is off, a long

activation applied to the DOWN input has no effect.

CONNECTION DIAGRAM - TOP VIEW

1

2

3

4

8

7

6

5

FIGURE 1

TRIG

)

DOWN

UP

DOZE

CAP

SYNC

August 1996

7534/35-080796-1

LSI/CSI

LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747

(631) 271-0400 FAX (631) 271-0405

UL

®

A3800

LS7534

LS7535