WT 8072 is a PIR (passive infra-red) controller, using analog mixing digital design technique and
manufactures by CMOS process which can either drive TRIAC or RELAY depending on users' choice.
With special noise immunity technique, WT8072 is the most stable PIR controller you can find on the
market. More than this, there are few components needed in its application circuit which can reduce
material cost and increase competitive.
*HIGH NOISE IMMUNITY.
*DRIVE EITHER RELAY OR TRIAC.
*ADJUSTABLE LIGHT ON DURATION.
*TRIAC CAN BE EITHER SHUNT OR SERIAL CONNECTED.
Pin No. Pin Name I/O
First stage OP amp output
2 NII 1
First stage OP amp positive input
3 II 1
First stage OP amp negative input
Stable reference voltage
Time base for 1. The delay time of receiving PIR singnal to sent a puls to
trigger TRIAC or a high signal to trigger relay.
The delay time = R x C x 32.
The PIR signal patented and accepted only if the signal cycle greater than R
x C x 768 .When state of relay or TRIAC is changing form active into
inactive mode. It takes more than R x C x 4069, then system is able to
receive PIR signal again.
2.The flash cycle show the beginning of auto mode.
Note: Width of TRIAC pulse = R x C x 2.
Flash cycle: R x C x 32768
10 K < R < 1M Ohm
100pF < C < 0.1 Uf (Reference Diagram 1)
For testing only
Weltrend Semiconductor, Inc.