TOUCH CONTROL LAMP DIMMER

DESCRIPTION:

LS7232ND is a MOS integrated circuit designed to control

brightness of incandescent lamps. The output of this IC controls

the brightness of a lamp by controlling the firing angle of a triac

connected in series with the lamp. All internal timings are syn-

chronized with the line frequency by means of a built-in phase-

lock loop circuit. The output occurs once every half-cycle of the

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

tioned anywhere between 158˚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

controlled by applying a low level at the SENS input or a high

level at the EXT input.

These functions may be implemented with very few interface

components, as shown in Figure 5. When implemented in this

manner, touching of the Touch Plate causes the lamp brightness

to change as follows:

1.

If the Touch Plate is touched momentarily (42ms to 333ms),

the lamp is:

a) turned off if it was on,

b) turned on if it was off.

The brightness resulting is either full brightness or,

depending on the mode, a previous brightness stored in the

IC memory.

2.

If the Touch Plate is touched

for a prolonged time

(more than 342ms) the light intensity changes slowly. As

long as the touch is maintained, the change continues; the

direction of change reverses whenever the maximum or

minimum brightness is reached.

INPUT/OUTPUT DESCRIPTION:

Supply voltage positive terminal.

MODE (Pin 2)

The LS7232ND can operate in either of 3 modes, Mode 0,

Mode 1 or Mode 2. A full description of the operating modes is

provided in Table 1. The MODE input level selects the operating

mode as follows:

1

2

3

4

8

7

6

5

TRIG

EXT

SENS

MODE

CAP

SYNC

FIGURE 1

PIN ASSIGNMENT - TOP VIEW

MODE Input

Mode

Functional Equivalent*

0

LS7231

Vss

1

LS7232

Float

2

LS7233

*NOTE:

The LS7232ND can replace LS7231, LS7232 and

LS7233 where the DOZE input is not used. The LS7232 PCB

requires no change. The LS7233 PCB requires that the Pin 2

connection be opened. The LS7231 PCB requires that the Pin

CAP (Pin 3)

The CAP input is for the PLL filter 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 ex-

ternal 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 activates this input (See Table 1) which controls the

turn-on, turn-off and conduction angle, Ø (See Figure 3), of the

TRIG signal with respect to the SYNC input.

EXT (Pin 6)

The EXT input is functionally identical to the SENS input except

that a high level activates this input. It is recommended that the

EXT input be used instead of the SENS input when long exten-

sion wires are employed between the IC and the Sensing Cir-

cuitry (See Figure 5 and Figure 6) because the EXT input is

less susceptible to noise.

7232ND-012703-1

January 2003

FEATURES:

• Phase-lock loop synchronization

allows use in Wall Switch applications.

• Provides brightness control of incandescent lamps

with touch plates or pushbutton switches.

• Controls the duty cycle from 23% to 88%

(conduction angles for AC half-cycles

between 41˚ and 158˚, respectively.)

• Operates at 50Hz/60Hz line frequency.

• Extension input for remote activation.

• LS7232ND (DIP); LS7232ND-S (SOIC ) - See Figure 1

LSI/CSI

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

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

LS7232ND

UL

®

A3800