ls7232nt LSI Computer Systems, Inc., ls7232nt Datasheet

ls7232nt

Manufacturer Part Number

ls7232nt

Description

Proximity/touch Control Halogen Lamp Dimmer

Manufacturer

LSI Computer Systems, Inc.

Datasheet

1.LS7232NT.pdf (7 pages)

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7232NT-042005-1

DESCRIPTION:

LS7232NT is a CMOS integrated circuit designed for brightness

control of incandescent lamps or tranformer coupled low voltage

halogen lamps. The brightness is controlled by controlling the fir-

ing angle of a triac in series with the lamp and triggered by the

LS7232NT. A Phase-Locked-Loop keeps the LS7232NT phase

pointer locked in phase with the line voltage.

A unique optical user interface provides for a smooth control of

the lamp intensity without the need for touching any sensor

plate. A mechanical switch interface for dimming control is also

provided which can be used for a remote touch plate. The IC in-

cludes features to address problems associated with inductive

loads such as transformers in low voltage halogen lamp applica-

tion. The voltage to current phase lag resulting from the in-

ductance may prevent the triac from shutting off at AC zero

crossover and/or prevent the triac from maintaining conduction

following the removal of the gate trigger. The inductive load

problems are addressed by the LS7232NT as follows:

1. Compensation for delayed triac cut-off.

2. Compensation for delayed triac turn-on.

3. Safety-Shutdown.

U L

A3800

FEATURES:

• Control of incandescent and transformer-coupled

• No-Touch lamp control through optical sensing

• PLL synchronization of AC for wall switch application.

• Extension input for remote control

• Safety-shutdown for transformer malfunction.

• Pin-selectable operating modes

• Single 5V power supply

• 50Hz/60Hz AC line frequency

• LS7232NT (DIP); LS7232NT-S (SOIC) - See Figure 1

LSI/CSI

low voltage halogen lamps.

PROXIMITY/TOUCH CONTROL HALOGEN LAMP DIMMER

At the set conduction angle, a triac trigger pulse of 130.2µs

(60Hz) is issued by the dimmer IC. If the triac fails to fire, a

second trigger pulse of 260.4µs width is issued 1 ms later

as a second attempt to fire the triac during the same half-

cycle.

If the frequency of occurrences of the delayed cut-off and

the delayed turn-on exceeds a preset threshold, a shut-

down is initiated by turning off the triac trigger pulses. The

safety-shutdown threshold value is accumulated in a 4-bit

Up/Down counter. The count increments for every oc-

currence of delayed cut-off or delayed turn-on and decre-

ments once every 8 SYNC pulses (AC line cycles). The

count will not decrement below zero. If the count reaches

15, the safety-shut-down is effected.

When trigger pulse is due to occur at a conduction angle

pulse is delayed until the triac has turned off. This elim-

inates the underlying cause of half-waving.

which coincides with the on-state of the triac, the trigger

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

The LS7232NT can be configured in 7 different modes of dim-

ming and timing off functions selected by two 3-state mode

pins.

INPUT/OUTPUT DESCRIPTION:

CAP (Pin 1)

PLL filter capacitor input. A 0.02µF capacitor is required at this

input for the optimal operation of the PLL.

SYNC (Pin 2)

The phase pointer for the triac trigger signal is synchronized

with the 50Hz/60Hz AC voltage applied at the SYNC input by

the internal PLL. The triac On/Off status information is also de-

rived from this input.

ANODE (Pin 3) CATHODE (Pin 4) and PHOTOUT (Pin 5)

These three pins constitute the input/outputs of a trans-

conductance and voltage amplifier pair (See Fig. 6) for con-

verting the current from a photo-diode to a voltage stimulus for

application at the SENS input. The photo-signal is used in lieu

of a touch plate for a touchless dimmer system. The output at

PHOTOUT is governed by the following equation:

Where V

A potentiometer is used for R

the photo-amplifier system.

= Current in Photo-diode connected between

= Supply Voltage

= Feedback resistance between PHOTOUT

CATHODE

PHOTOUT

REMOTE

ANODE and CATHODE

and CATHODE

LS7232NT

ANODE

OUT

SYNC

SENS

CAP

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

PIN ASSIGNMENT - TOP VIEW

= V

/2 + 2I

LS7232NT

FIGURE 1

for controlling the sensitivity of

1 4

1 3

1 2

1 1

1 0

LEDO

T R I G /

V s s ( - V )

April 2005

(+V)

Related parts for ls7232nt

ls7232nt Summary of contents

Page 1

... PHOTOUT SENS 6 7 REMOTE FIGURE 1 The LS7232NT can be configured in 7 different modes of dim- ming and timing off functions selected by two 3-state mode pins. INPUT/OUTPUT DESCRIPTION: CAP (Pin 1) PLL filter capacitor input. A 0.02µF capacitor is required at this input for the optimal operation of the PLL. ...

Page 2

... SENS (Pin 6) A positive signal applied at the SENS input controls the turn-on, turn-off and dimming function of the LS7232NT. The SENS in- put is designed to operate with very low levels of signal, so that it can be directly interfaced with the photoamplifier output. Sig- nal at the SENS input is amplified with a gain of 30 photo- sensor is not to be used, the SENS input can easily be adapted to a touch plate ...

Page 3

ABSOLUTE MAXIMUM RATINGS: PARAMETER SYMBOL DC Supply Voltage Any Input Voltage Operating Temperature Storage Temperature DC ELECTRICAL CHARACTERISTICS: PARAMETER SYMBOL Supply Voltage Supply Current Input Logic Levels: SYNC Lo SYNC Hi REMOTE Lo REMOTE Hi SENS Lo SENS Hi RC ...

Page 4

PARAMETER Timer Resistor Timer Capacitor Timer Delay Slew Off Rate Slew Off Delay Pre-Off Delay (Mode 7) Slew-Off Delay (Mode 7) LEDO Pulse Width SYNC to LEDO delay LEDO to TRIG/ delay LEDO to Strobe delay SYNC (Idealized) TRIG/ t ...

Page 5

SHORT SHORT SENS t s 155 MODE OFF t 1 155 MODE OFF t 2 155 MODE OFF SHORT SHORT SENS 155 MODE OFF ...

Page 6

... DECODER FIGURE 7 . PHOTO AMPLIFIER WITH PHOTO DIODE AND GAIN RESISTOR , ANODE 7232NT-012703-6 CONTROL PHASE MEMORY Ø POINTER AMP TIMER FIGURE 6. LS7232NT BLOCK DIAGRAM 100K AMP + AMP - 100K CATHODE DIGITAL TRIGGER COMPARATOR LOGIC IR PULSE LOGIC AMP ...

Page 7

... C7 = 0.003µF, 10V C8 = 0.1µF, 10V R1 = 270 , 1/ 680k , 1/ 1. 500k , 1/8W Pot 1/ 1/4W 7232NT-042005 LS7232NT 200 1/ 1/4W (1) All components are the same as 115V except as listed below: R8 2.7M , 1/4W R10, R11 = 2.7M , 1/4W R12 = 200k , 1/4W R13 = 2k , 1/4W ...

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