PT8A2641 Datasheet, PDF (7/13 Pages) Pericom Semiconductor Corporation – PIR Sensor Light Switch

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PT8A2641-2642/2645-2648
PIR Sensor Light Switch
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Power on initial: Because the band-pass filter and amplifier require a warm up period to reach a stable state after power-on so
any inputs should be ignored during this period.
In the AUTO mode within the first 10 seconds of power-on initialization, the system allows override control to access the
quickly install mode. However, after 40 seconds of the initial time the system allows override control between ON and AUTO.
It will remain in the warm up period if the total initial time has not elapsed after returning to AUTO.
In case that the ZC signal disappears more than 3 seconds, the chip will restart the initialization operation. However, the restart
initial time is always 40 seconds and cannot be extended by adding CRST to the RSTB pin as shown in Fig.5.
MODE: a tri-state input pin used to select the operating mode.
MODE
VCC
GND
Open
Operating Mode
Output always ON
Output always OFF
AUTO
Description
RELAY outputs high at ZC rising edge
TRIAC outputs negative pulse train with synchronizing to ZC
RELAY outputs low
TRIAC outputs high
Outputs remain off state until activated by a valid PIR trigger signal. When working in
the AUTO mode, the chip allows override control by switching the ZC signal. MODE
outputs square wave with frequency of 31.25Hz.
ZC: a CMOS input structure. It receives AC line frequency and generates zero crossing pulses to synchronize the triac/relay
driver. With an effective ZC signal switching (switch OFF/ON 2 times within 3 seconds), the system provides the following
additional functions:
Quickly install mode: Within 10 seconds after power-on, effective ZC switching will force the chip to enter the quickly
install mode. During the mode, the outputs will be active for a duration of 1.3 seconds each time a valid PIR trigger signal
is received. If a time interval exceeds 32 seconds without a valid trigger input, the chip will enter the AUTO mode
automatically.
Figure 6 Test mode
RSTB
Test enable
ZC
COMPO
10s
40s warm up time
<3s
>0.34s
Relay
(Triac) OFF
*
ON
ON
1.3s 2s 1.3s
**
ON
ON
1.3s _2s 1.3s
>32s
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Override control: When the chip is working in the AUTO mode (MODE= open), the output is activated by a valid PIR trigger
signal and the active output duration is controlled by the OSCD oscillating period. The lamp can be switched always to “ON”
from the AUTO mode by either switching the MODE pin to VCC or switching the ZC signal by an OFF/ON operation of the
power switch (OFF/ON twice within 3 seconds). The term "override" refers to the change of operating mode by switching the
power switch. The chip can be toggled from ON to AUTO by an override operation. Shows as figure 7.
If the chip is overridden to ON and there is no further override operation, it will return to AUTO automatically after an
internal preset ON time duration has elapsed. This override ON time duration is set to 5 hours, refer to fig 7.
The PT8A2641/5/7 will flash on output pin when changing the operating mode. It will flash 3 times at a 1Hz rate each time
the chip changes from the AUTO mode to another mode or flash 3 times at a 2Hz rate when returning to the AUTO mode.
But
PT8A2642//6/8 does no flash at the same condition.
However, if the AUTO mode is changed by switching the MODE switch output will not flash.
12-07-0006
PT0192-3 07/06/12
7