10-08-2012, 09:56 AM
PIR Sensor Light Switch Controller
[attachment=30863]
General Description
The PT8A261 and PT8A262 are low power mixed
signal CMOS LSI designed for the automatic lamp
control using PIR sensor as motion detector.
With on chip noise filter and voltage regulator, the IC
provides stable operations throughout temperature
range. CDS input to disable day time operation is
desired.
Functional Descriptions
The PT8A261 and PT8A262 are CMOS LSI chips designed for
automatic PIR lamp control. They can operate in 2-wire configuration
for triac applications or in 3-wire configuration for
relay applications.
The device consists of operational amplifiers, a comparator,
timer, a zero crossing detector, control circuit, a voltage regulator,
a system oscillator, and an output timing oscillator.
The PIR sensor detects infrared power variations caused by
motion of a human body and transfer to a voltage variation. If
the PIR output voltage variation conforms to criteria, the lamp
is turned on for an adjustable duration. The PT8A261 (or 262)
offers three operating modes (ON, AUTO, OFF) which can be
set through a MODE pin. When the device is working in AUTO
mode, the user can override the mode to switch it to TEST
mode or manual ON mode, or return to the AUTO mode by
switching power switch.
OSCS and OSCD Pins
OSCS is a system oscillator I/O pin connected to an external
RC to generate system frequency of 16kHz.
OSCD is an output timing oscillator I/O pin. It’s connected to
an external RC to obtain the desired turn-on duration by selecting
various values of RC or using a variable resistor.FOSCD
is the frequency of OSCD pin, output timing can be caculated
as the formula: TD = 21504/FOSCD
CDS Input Circuit
CDS is a CMOS schmitt trigger input pin. It is used to distinguish
between day time and night time. When the input voltage
of CDS is high the PIR input is enabled, when CDS low the
PIR input disabled. The input disable-to-enable debounce
time is 5 seconds. Connect this pin to VCC when not using it.
The CDS input is ignored when the TRIAC or RELAY output
is active.
MODE
MODE is a tri-state input pin for operation mode selection.
See the following table 3.
Override Control: The term “override” refers to the change of
operating mode by switching the power switch twice within 3
seconds. When the chip is working in the AUTO mode (MODE
pin openned), the output is activated by a valid PIR trigger
signal and the output active duration is controlled by the OSCD
oscillation period. The lamp can be switched to ON from the
AUTO mode by either switching the MODE pin to VCC or
switching the power switch twice within 3 seconds.
[attachment=30863]
General Description
The PT8A261 and PT8A262 are low power mixed
signal CMOS LSI designed for the automatic lamp
control using PIR sensor as motion detector.
With on chip noise filter and voltage regulator, the IC
provides stable operations throughout temperature
range. CDS input to disable day time operation is
desired.
Functional Descriptions
The PT8A261 and PT8A262 are CMOS LSI chips designed for
automatic PIR lamp control. They can operate in 2-wire configuration
for triac applications or in 3-wire configuration for
relay applications.
The device consists of operational amplifiers, a comparator,
timer, a zero crossing detector, control circuit, a voltage regulator,
a system oscillator, and an output timing oscillator.
The PIR sensor detects infrared power variations caused by
motion of a human body and transfer to a voltage variation. If
the PIR output voltage variation conforms to criteria, the lamp
is turned on for an adjustable duration. The PT8A261 (or 262)
offers three operating modes (ON, AUTO, OFF) which can be
set through a MODE pin. When the device is working in AUTO
mode, the user can override the mode to switch it to TEST
mode or manual ON mode, or return to the AUTO mode by
switching power switch.
OSCS and OSCD Pins
OSCS is a system oscillator I/O pin connected to an external
RC to generate system frequency of 16kHz.
OSCD is an output timing oscillator I/O pin. It’s connected to
an external RC to obtain the desired turn-on duration by selecting
various values of RC or using a variable resistor.FOSCD
is the frequency of OSCD pin, output timing can be caculated
as the formula: TD = 21504/FOSCD
CDS Input Circuit
CDS is a CMOS schmitt trigger input pin. It is used to distinguish
between day time and night time. When the input voltage
of CDS is high the PIR input is enabled, when CDS low the
PIR input disabled. The input disable-to-enable debounce
time is 5 seconds. Connect this pin to VCC when not using it.
The CDS input is ignored when the TRIAC or RELAY output
is active.
MODE
MODE is a tri-state input pin for operation mode selection.
See the following table 3.
Override Control: The term “override” refers to the change of
operating mode by switching the power switch twice within 3
seconds. When the chip is working in the AUTO mode (MODE
pin openned), the output is activated by a valid PIR trigger
signal and the output active duration is controlled by the OSCD
oscillation period. The lamp can be switched to ON from the
AUTO mode by either switching the MODE pin to VCC or
switching the power switch twice within 3 seconds.