BX604 is a pyroelectric infrared
sensor that integrates a digital intelligent control circuit and a human
detection sensor in an electromagnetic shielding housing. The human
body detection sensor couples the sensed human movement signal to the
digital intelligent integrated circuit chip through a very high
impedance differential input circuit, which converts the signal into an
ADC digital signal, and when the PIR signal exceeds the selected digital
threshold, there is a timed REL level output. The OEN enable allows the
REL output to be automatically controlled via a light sensor. The
sensitivity and time parameters are set by a voltage divider resistor.
All signal processing is done on the chip.