Digital infrared sensor p924-s series

Product model: p924ss / p924ms / p924bs / p904bs

Product No.: p924ss / p924ms / p924bs / p904bs

Product features: adjustable sensitivity, output digital signal

Application: smart home, network camera, wireless communication induction products

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The p924-s series of digital intelligent pyroelectric sensors adopts the special analog-to-digital hybrid processing integrated circuit as the built-in processing chip. The integrated circuit combines the complete functions required by a single passive infrared pyroelectric moving detector.

The input with high input impedance is used to connect the pyroelectric sensitive element. The pyroelectric signal is converted into a 16 bit digital signal and further processed by digital band-pass filtering. Then the moving detection signal is obtained by comparing with the adjustable threshold. The moving detection signal is output from a push-pull rel output. The sensitivity can be set by DC voltage at the corresponding input end The voltage at the setting terminal is converted to a digital value with 7-bit resolution, and all signal processing is completed on the chip.

Product introduction product parameters

characteristic:

1. The pyroelectric signal is processed by digital signal processing technology.

2. Two channel differential high input impedance input is used as sensor sensitive element input.

3. A 16 bit high precision AD converter is used to convert the voltage signal generated by the sensitive element into digital signal.

4. A second-order Butterworth band-pass filter is used to filter the digital signal output from AD converter, which can effectively filter the low-frequency and high-frequency noise caused by various reasons.

5. Because the signal processing is completed in the shielded tube shell, it has a stronger ability to resist RF interference.

6. The sensitivity threshold can be adjusted by external voltage divider.

7. Low voltage, low power consumption.

Internal schematic diagram:

Schematic circuit diagram:

Trigger event processing mode:

When the infrared signal received by the sensor exceeds the internal trigger threshold, a count pulse will be generated. When the signal is received again, it will be considered that it has received the second pulse. Once two pulses are received within 4 seconds, the rel pin of the sensor will output a high level to indicate that there is a signal. In addition, as long as the received signal amplitude is more than 5 times of the trigger threshold, only one pulse is needed to trigger the rel output high level. If the trigger signal is received continuously, the holding time of rel high level starts from the last effective trigger, and the time delay is about 2.3 seconds.

Sensitivity / threshold:

Relationship between voltage and internal threshold of sens

The voltage applied at the end of sens determines the internal threshold. If the sens is connected to zero and reaches the maximum sensitivity, the internal threshold value is 49uv. If the voltage applied by sens is greater than VDD / 4, the maximum internal threshold value is 462uv.