FEATURES:

• Direct Interface with PIR Sensor

• Two-Stage Differential Amplifier

• Amplifier Gain and Bandwidth externally controlled

• Window Comparator and Digital Filter limit Noise

• Triac Output Drive

• Programmable Output Duration Timer

• Selectable Dead Time

• Single or Dual Pulse Detection

• Timing derived from 50Hz/60Hz AC

• Motion Detection LED Indicator

• LS6505 (DIP), LS6505-S (SOIC)- See Figure 1

APPLICATIONS:

Wall and ceiling mounted occupancy sensors providing

energy savings and convenience.

DESCRIPTION (See Figure 2)

The LS6505 is a CMOS integrated circuit, designed for detecting

motion from a PIR Sensor and initiating appropriate responses.

DIFFERENTIAL AMPLIFIER

Each stage of the two stage Differential Amplifier can be set to

have its own amplification and bandwidth. The two inputs to the

first stage allow for single ended or differential connection to PIR

Sensors. This stage can be biased anywhere in its dynamic range.

The second stage is internally biased so that the Window Compar-

ator’s lower and higher thresholds can be fixed relative to this bias.

WINDOW COMPARATOR

The Window Comparator provides noise filtering by enabling only

those signals equal to or greater than a fixed threshold at the out-

put of the Differential Amplifier to appear at the output of the

Window Comparator.

COMPARATOR DIGITAL FILTER

The output of the Window Comparator is filtered so that motion

must be present for a certain duration before it can be recognized

and appear as pulses at the Digital Filter output.

SINGLE PULSE / DUAL PULSE MODES

The logic level at the Pulse Mode Select input selects Single Pulse

(SP) or Dual Pulse (DP) mode. The trigger for the Output Duration

Timer is generated by requiring one (SP Mode) or two (DP Mode)

pulses to be present at the Digital Filter output within a specified

time period. SP Mode = 0; DP Mode = 1

OUTPUT DURATION TIMER (See Table 1 and Figure 3)

The timeout is selected by the voltage level at the Timer Control in-

put. The Timer’s trigger is generated from pulses at the Digital filter

output. In Auto operation, the Timer controls the On duration of the

Triac output and is retriggerable.

DEAD TIME (See Table 2)

False turn-ons are prevented from occurring by establishing a

Dead Time between the end of the timeout of the Output Duration

Timer and the retriggering of that Timer.

TRIAC OUTPUT

This open drain output turns On when the Output Duration

Timer is triggered. The output drives a Triac gate. With the Out-

put Duration Timer On and a 2.7V P-P 60Hz signal applied to

the AC input, this output produces a negative going pulse in

each half-cycle delayed a nominal 1.2ms from the zero crossing.

There is no more than 150us difference between the zero-

crossing delay of each pulse.

WARNING OUTPUT

This output goes high for 2 sec beginning 7.5 sec before the

Triac output turns off. This signal can be used to trigger an

audible or visual alert.

LED OUTPUT (See Figure 3)

Normally, the status of the LED output is opposite to the Triac

output, but in Auto operation the LED output flashes on for one

second whenever motion is detected.

MODE SELECT

OPERATION SELECT (See Figure 3, S1)

The 3-state Operation Select input determines the operation of

LS6505 in accordance with the selected Mode as shown below:

Input

Mode A

Mode B

Mode C

On

(1)

(3)

Open

Auto

Prior Condition

Auto

Vss

Off

(2)

(4)

starts Auto operation. After the Triac output is off for 15

seconds, Auto operation terminates.

(2) Momentary application of Vss turns off the Triac output.

(3) Same as (1) except that Auto operation does not terminate.

(4) Same as (2) except that after the Triac output is off for 8

seconds, Auto operation begins.

PIR SENSOR INTERFACE

November 2002

6505-110602-1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

DIFF. AMP. 2 INPUT (-)

DIFF. AMP. 2 OUTPUT

AC INPUT

TRIAC OUTPUT

DIFF. AMP 1 INPUT (-)

DIFF. AMP 1 INPUT (+)

TIMER CONTROL INPUT

DEAD TIME SELECT INPUT

OPERATION SELECT INPUT

PULSE MODE

SELECT INPUT

LED OUTPUT

PIN ASSIGNMENT - TOP VIEW

FIGURE 1

DIFF. AMP. 1 OUTPUT

15

16

MODE SELECT INPUT

WARNING OUTPUT

LSI/CSI

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

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

LS6505

UL

®

A3800