pt8a262w Pericom Technology Inc, pt8a262w Datasheet - Page 5

• Manufacturer Part Number: pt8a262w
• Description: Pir Sensor Light Switch Controller
• Manufacturer: Pericom Technology Inc

PT0075(04/03)
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Functional Descriptions
The PT8A261 and PT8A262 are CMOS LSI chips designed for
automatic PIR lamp control. They can operate in 2-wire con-
figuration 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 regu-
lator, 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.
Figure 5. CDS Input Circuit
Figure 6. CDS Enable Debounce
Figure 3. System Oscillator
Rp
V
CC
CDS
CDS
R
C
S
S
200P
560K
Schmitt
Driver
OSCS
CDS
PIR
CDS
PT8A261/262
Enable
PT8A261/
Control
Circuit
262
Disable
5
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 se-
lecting various values of RC or using a variable resistor.F
is the frequency of OSCD pin, output timing can be caculated
as the formula:
CDS Input Circuit
CDS is a CMOS schmitt trigger input pin. It is used to distin-
guish between day time and night time. When the input volt-
age 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 V
The CDS input is ignored when the TRIAC or RELAY output
is active.
Figure 4. Output Timing Oscillator
Table 2. CDS Pin Function
PIR Sensor Light Switch Controller
HIGH
LOW
CDS
< 5s
R
C
D
D
T
D
= 21504/F
> 5s
OSCD
Day Time
T
Status
Night
D
Enable
= 21504/F
OSCD
PT8A261/
262
PT8A261/262
CC
OSCD
Data Sheet
when not using it.
Disabled
Enabled
PIR
Ver:5
OSCD