LSI/CSI
UL
®
LS6511
(631) 271-0400 FAX (631) 271-0405
October 2002
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
A3800
PIR SENSOR INTERFACE
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.
6511-102502-1
PIN ASSIGNMENT - TOP VIEW
DIFF. AMP. 1 OUTPUT
DIFF. AMP. 2 INPUT (-)
DIFF. AMP. 2 OUTPUT
DIGITAL FILTER RC
CP MODE / DP MODE RC
LSI
1
2
3
14
13
12
DIFF. AMP 1 INPUT (-)
DIFF. AMP 1 INPUT (+)
5V REGULATOR OUTPUT
V
DD
(+V )
V
SS
(-
V
)
LED/RELAY OUTPUT
LED/RELAY OUTPUT
LS6511
4
5
11
10
9
8
DURATION TIMER RC 6
MODE SELECT
7
FIGURE 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
positive voltage (V
DD
to 9.5V maximum).
SHUNT REGULATOR
The LS6511 includes a 5V Shunt Regulator Output which can be
tied to the V
DD
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 [ LSI COMPUTER SYSTEMS ]
