FEATURES:

• Direct Interface with PIR Sensor

• Two-Stage Differential Amplifier

• Amplifier Gain and Bandwidth externally controlled

• True and Complementary Output Drives

• Separate digital filters for processing positive and

negative input signals

• Single Pulse/Dual Pulse/ Concurrent Pulse Detection

• Adjustable Output Pulse Width

• Optional 5V Shunt Regulator Output

• 50µA Typical Supply Current

• Undervoltage Detection

• LS6511(DIP); LS6511-S (SOIC) - See Figure 1

APPLICATIONS:

Security system intrusion detection, automatic doors, motion

triggered events such as remote animal photography.

DESCRIPTION (See Figure 5)

The LS6511 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

Comparator’s lower and higher thresholds can be fixed relative to

this bias. Signal levels as low as 100µV can be detected.

WINDOW COMPARATOR

The Window Comparator provides noise filtering by enabling only

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

output of the Differential Amplifier to appear at the 2 outputs of

the Window Comparator. One output detects positive input

signals while the other output detects negative input signals.

COMPARATOR DIGITAL FILTER

The outputs of the Window Comparator are filtered so that

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

recognized and appear as pulses at the Digital Filter outputs. An

external RC network sets the duration time. Nominal duration is

50ms.

MODE SELECT

A tristate input pin selects how the detected signals are

processed. Single Pulse (SP) Mode is when detection from either

a positive or negative input signal at the Digital Filter outputs will

cause an LED/RELAY output to occur. Concurrent Pulse (CP)

Mode is when detection from a positive and negative input signal

must occur within a specific time before an output will occur.

Dual Pulse (DP) mode is when any two detections within a

specific time will cause an output to occur.

SP Mode = 0; CP Mode = Open; DP Mode = 1.

PIR SENSOR INTERFACE

September 2006

6511-090606-1

PROGRAMMABLE RETRIGGERABLE ONE-SHOTS

Positive and negative input signals at the digital filter outputs will

generate retriggerable one-shot pulses. In the Concurrent Pulse

Mode, outputs from each one-shot must occur together at some

point in time to cause an output to occur. The one-shot pulse

width is programmable using an external RC network. Typical

pulse widths used vary between 1 and 12 seconds.

WINDOW TIMER

In the Dual Pulse Mode any two detections must occur within a

timing window to cause an output to occur. The timing window is

programmable using an external RC network. Typical windows

are between 1 and 5 seconds.

OUTPUT DURATION TIMER

The duration timer is retriggerable and programmable using an

external RC network. Typical duration times are between 0.5 and

15 seconds. Successive input detections will restart the timer.

OUTPUTS

The LED/RELAY Output is an open drain output that will sink

current when an input signal is detected and processed and

when the Power Supply drops below 3.7V (Typical) (Under-

voltage Detection). The Undervoltage Detection will be removed

when the Power Supply rises above 3.9V (Typical). The LED/

RELAY Output performs identically but is opposite in polarity.

The output can sink current from a relay coil returned to a

SHUNT REGULATOR

The LS6511 includes a 5V Shunt Regulator Output which can be

higher voltage power supply.

Note: See Figures 2, 3 and 4 for application schematics.

LSI/CSI

LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 (631) 271-0400 FAX (631) 271-0405

LS6511

UL

®

A3800

1

2

3

4

5

6

7

8

9

10

11

12

13

14

DIFF. AMP. 2 INPUT (- )

DIFF. AMP. 2 OUTPUT

CP MODE / DP MODE RC

DIGITAL FILTER RC

DIFF. AMP 1 INPUT (-)

DIFF. AMP 1 INPUT (+)

5V REGULATOR OUTPUT

MODE SELECT

DURATION TIMER RC

LED/RELAY OUTPUT

PIN ASSIGNMENT - TOP VIEW

FIGURE 1

DIFF. AMP. 1 OUTPUT

LED/RELAY OUTPUT

(+V)

(- V)