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

January 2003

6511-012703-1

LSI

LS6511

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

)

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
positive voltage (V

to 9.5V maximum).

SHUNT REGULATOR
The LS6511 includes a 5V Shunt Regulator Output which can be
tied to the V

Pin so that the circuit can be powered from a

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

A3800

ABSOLUTE MAXIMUM RATINGS:

PARAMETER

SYMBOL

VALUE

UNIT

DC supply voltage

DD -

Any input voltage

- 0.3 to V

+ 0.3

Operating temperature

-40 to +85

°C

Storage temperature

STG

-65 to +150

°C

ELECTRICAL CHARACTERISTICS:
(All voltages referenced to V

, T

= -40°C to +55°C, 4.5V

6.5V, unless otherwise specified.)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNIT

CONDITIONS

SUPPLY CURRENT:

µA

LED/RELAY, LED/RELAY

4.5V - 6.5V

125

µA

and REGULATOR
outputs not loaded

REGULATOR:

Voltage

5.00

5.75

6.25

Current

DIFFERENTIAL AMPLIFIERS:

Open Loop Gain, Each Stage

Common Mode Rejection Ratio

MRR

Power Supply Rejection Ratio

SRR

Input Sensitivity

100

µVp-p

= 25°C, with Amplifier

(Minimum Detectable Voltage

Bandpass configuration

to first amplifier when both

as shown in Figure 3

amplifiers are cascaded for
a net gain of 8,000)

Input Dynamic Range

1.75

Diff. Amp 2 Internal

0.3V

Reference

COMPARATOR:

Lower Reference

THL

- 0.8V

At V

= 5.75V

Higher Reference

THH

+ 0.8V

At V

= 5.75V

DIGITAL FILTER:
For 50ms Filter Time

2.2

0.01

µF

ONE SHOT

2.2

(1 Second)

0.22

µF

WINDOW TIMER

2.2

(2.5 Second)

0.68

µF

DURATION TIMER

2.2

(5 Seconds)

0.68

µF

OUTPUT DRIVE CURRENT

-20

= 5V

(Vo = 0.5V Max.)

6511-012703-2

The information included herein is believed to be
accurate and reliable. However, LSI Computer Systems,
Inc. assumes no responsibilities for inaccuracies, nor for
any infringements of patent rights of others which may
result from its use.

FIGURE 2. TYPICAL RELAY APPLICATION

R1 = See NOTE 2
R2 = 36k

R3 = 2.7M

R4 = 36k

R5 = 2.7M

C1 = 100µF
C2 = 33µF
C3 = 0.01µF
C4 = 33µF
C5 = 0.01µF
C6 = 0.01µF (Typical)
C7 = 0.22µF (CP Mode; Typical)
C7 = 0.68µF (DPMode; Typical)
C8 = 0.22µF (Typical)
C9 = 0.1µF
D1 = 1N4001
RELAY = No typical P/N

PIR = HEIMANN LHi 958, 968 (Typical)

All Resistors 1/4W.

All Capacitors 10V.

NOTE 2: R1 is selected to provide sufficient
current to drive the LS6511 and PIR Sensor. Any
surplus current is available to drive additional
loads applied to the 5V Shunt Regulator output or
is absorbed by the 5V Shunt Regulator. Refer to
specifications for current limits.

NOTE 3: In SP Mode, R7 and C7 are not used
and Pin 5 is tied to Vss.

R6 = 2.2M

(Typical)

R7 = 2.2M

(Typical)

R8 = 2.2M

(Typical)

R9 = 3k

R10 = 2.2k

(Typical)

NOTE 1: The relay coil is normally energized and the LED is off.
When an alarm occurs, the relay coil becomes de-energized and
the LED is turned on.

AMP 1
OUT

AMP 1

(-)IN

AMP 2
(-)IN

AMP 1

(+)IN

AMP 2
OUT

5V REG

OUT

CP MODE or
DP MODE RC

L E D / R E L

OUT

PIR
S E N S O R

LS6511

L E D / R E L

OUT

MODE

DIG FILTER
RC

DUR TIM
RC

RELAY
COIL

RAW
DC
INPUT

R10

LED

S = 3-Position SPDT (On-Off-On)

See Note 3

Using the typical application circuit as shown in Figure 2,
the Outputs on Pins 8 and 9 occur on power-up because of
the large settling time in the amplifier stages. In applications
where this is not desireable, the digital filter oscillator must
be disabled on power-up long enough to enable the PIR
amplifiers to stabilize. Replacing the R6-C6 circuit shown in
Figure 2 with the circuit shown in Figure 3 will disable the
digital filter oscillator until the voltage across the 220µF
capacitor reaches a value high enough for the oscillator to
begin oscillating. Component values that can be changed to
speed up stabilization include C2, C3, C4 and C5. C3 and
C5 become 0.001µF and C2 and C4 become 10µF.

FIGURE 3. INHIBITING OUTPUTS UPON POWER TURN-ON

L S 6 5 1 1 - 4

2 . 2 M

. 0 1 µ F

2 2 0 µ F

1 0 0 k

6511-012703-3

NOISE CONSIDERATIONS
Layout of any circuit using a high-gain PIR amplifier is critical.
The PIR amplifier components should be located close to the
amplifier pins on the chip in order to minimize noise pickup.The
oscillator and relay drive components should be located away
from the amplifier components.

Other steps that can help reduce noise is adding a ground
shield backplane to the PCB and enhancing the filtering of
VDD; i.e., adding a 0.1uF high frequency capacitor across C1
and increasing C1 to 220 µF.

6511-012703-4

A M P 1
OUT

A M P 1

(-)IN

A M P 2
(-)IN

A M P 1

(+)IN

A M P 2
OUT

5 V R E G

OUT

PIR
S E N S O R 1

L S 6 5 1 1

R10

PIR
S E N S O R 2

R1 = 1k

R6 = 36k

C1 = 100µF

C6 = 33µF

R2 = 2.7M

R7 = 36k

C2 = 0.01µF

C7 = 0.01µF

R3 = 36k

R8 = 36k

C3 = 33µF

C8 = 0.1µF

R4 = 2.7M

R9 = 5.6M

C4 = 0.01µF

C9 = 0.1µF

R5 = 36k

R10 = 2.4M

C5 = 33µF

PIRs = HEIMANN LHi 954, 958, 978, 874 or 878 (Typical)

All Resistors 1/4 W. All Capacitors 10V.
NOTES: 1) A pair of PIR Sensors may be used in applications where a wider optical field of view is needed.

2) External 5V Regulator drives the LS6511 and PIR sensor.

FIGURE 4. DIFFERENTIAL INTERFACE TO PIR SENSOR PAIR

AMP

COMP

DIFF AMP 2
OUTPUT

DIFF AMP 2
INPUT (-)

DIFF AMP 1
OUTPUT

DIFF AMP 1
INPUT (-)

DIFF AMP 1
INPUT (+)

SHUNT

REGULATOR

PROGRAMMABLE
RETRIGGERABLE
ONE-SHOT

OUTPUT
DURATION
TIMER

WINDOW
TIMER

5 V REGULATOR
OUTPUT

CONCURRENT PULSE/
DUAL PULSE RC

LED/RELAY
OUTPUT

DRIVER

M
U
X

FIGURE 5. LS6511 BLOCK DIAGRAM

WINDOW

COMPARATOR

DIGITAL
FILTER

PROGRAMMABLE
RETRIGGERABLE
ONE-SHOT

LED/RELAY
OUTPUT

DRIVER

DIGITAL FILTER RC

MODE
SELECT

DURATION
TIMER RC

)

UNDERVOLTAGE
DETECTOR

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ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LS6511-S