S918-H Digital Intelligent Pyroelectric Infrared Sensor
S918-H is a pyroelectric infrared sensor that integrates a digital intelligent control circuit and a human detection sensitive element in an electromagnetic shielding cover. The human detection sensitivity element couples the sensed human movement signal to the digital intelligent integrated circuit chip through the very high impedance differential input circuit. The digital intelligent integrated circuit converts the signal into a 15-bit ADC digital signal when the PIR signal exceeds the selected digital valve. When there is a value, there will be a regular REL level output. The OEN enable enables the REL output or automatic control through the light sensor. Sensitivity and time parameters are set by resistors and correspond to corresponding values, and their voltage is converted into a digital threshold with 7-bit resolution. All signal processing is done on the chip.
①Digital signal processing
②Enable power regulation for more energy savings
③Two-way differential very high impedance sensor input
④A second-order Butterworth band-pass filter with built-in infrared sensors shields input interference from other frequencies
⑤High power supply rejection ratio, anti-radio frequency interference
⑥Sensitivity, timing, light sensor Schmitt REL output
⑦LED sensor dynamic output port
⑧Low voltage, low power consumption, instant work after startup
Ⅱ IoT sensor
Ⅲ Digital Frame
Ⅳ Sensor light
Ⅴ TV, fridge, air conditioning
Ⅵ Web video camera
Ⅶ USB alarm
Ⅷ PIR motion detection
Ⅸ Intrusion detection
Ⅹ Occupancy detection
Ⅺ Interior lights, corridors, buildings, private alarms
Ⅻ LAN Monitor
ⅰ Car theft
4. Performance parameters
①Maximum rated value
Any electrical stress exceeding the parameters in the table below may cause permanent damage to the device. Working under these maximum rated conditions may affect the reliability of the device.
|Current into any pin||Into||-100||100||mA|
②Working conditions (T=25°C, VDD=3V, unless otherwise specified)
|Sensitivity Threshold Value||Vsens||120||μV||Non-adjustable|
|Output Low Current||IOL||10||120||mA||VOL<1V|
|Output High Current||IOH||-10||mA||VOH>(VDD-1V)|
|REL Low Level OutputBlockade Time||TOL||2.3||s||Non-adjustable|
|REL High Level OutputDelay Time||TOH||2.3||s|
|Oscillator & Filter|
|Low pass filter cut-off||7||hz|
|High pass filter cut-off
|Oscillator frequency onChip||FCLK||64||kHz|
Interior Block Diagram
4. output trigger mode
When the pyroelectric infrared signal received by the probe exceeds the trigger threshold inside the probe, a count pulse will be generated internally. When the probe receives this signal again, it will think that it has received the second pulse. Once it receives 2 pulses within 4 seconds, the probe will generate an alarm signal and the REL pin will trigger high. . In addition, as long as the amplitude of the received signal exceeds more than 5 times the trigger threshold, only one pulse is needed to trigger the REL output. The following figure shows an example of a trigger logic diagram. For multiple triggers, the output REL is held from the last valid pulse.
5. Extended time ONTIME
The voltage applied at the ONTIME terminal determines the delay time for the REL to maintain the high output signal after the sensor is triggered. Each time the trigger signal is received, the delay time starts counting again, due to the dispersion of the internal oscillator frequency, the delay time. There will be a certain range of error.
6. Sensitivity setting
The voltage at the SENS input sets the sensitivity threshold, which is used to detect the strength of the PIR signal at the PIRIN and NPIRIN inputs. When grounded, it is the minimum voltage threshold and the sensitivity is the highest. Any voltage exceeding VDD/2 will select the maximum threshold, which is the lowest sensitive setting for PIR signal detection, that is, the sensing distance may be minimum. It should be pointed out that the infrared sensor sensing distance and
SENS input voltage is not a linear relationship, its distance and the sensor’s own signal to noise ratio, Fresnel lens imaging object distance, moving body’s background temperature, ambient temperature, environmental humidity, electromagnetic interference and other factors form a complex and multiple relationship, that is, can not The output result is judged by a single index, and the actual debugging results shall prevail. The lower the SENS pin voltage is, the higher the sensitivity is, and the farther the sensing distance is. The S918-H has a total of 32 sensing distances, and the nearest sensing distance can reach centimeters. In actual use, the sensitivity can be adjusted by using a resistor divider.
5.Transmission spectrum of window material
7.Typical application circuit
Note: This circuit is a reference circuit for the S918-H digital intelligent pyroelectric infrared sensor.
❶ S918-H is a pyroelectric infrared sensor that detects infrared changes. Detection of a heat source other than the human body or a change in the temperature and movement of the heat source may not be possible. Need to pay attention to the following general matters. Please be sure to check the performance and reliability with the actual usage status.
1) When detecting heat sources other than the human body
(1) When a small animal enters the detection range
(2) Far-infrared direct-irradiation sensors such as sunlight, car headlights, and incandescent lamps
(3) When the temperature in the detection range changes drastically due to the warm air of the cold-greenhouse equipment, cold air, and water vapor of the humidifier, etc.
2) When it is difficult to detect the heat source
(1) When there is a material such as glass or acrylic that is difficult to transmit far-infrared rays between the sensor and the detection object
(2) The heat source in the detection range is hardly actuated or moves at a high speed.
❷When the inspection area is enlarged
When the ambient temperature and the human body temperature are relatively large (approximately 20°C or more), even in the specified detection range
In addition, there are sometimes broad detection areas.
❸About other uses
1) If there is a stain on the window, it will affect the detection performance, so please pay attention.
2) The lens is made of soft material (polyethylene). If a load or impact is applied to the lens, it will cause malfunction and deterioration of performance due to deformation and damage. Therefore, avoid the above situation.
3) Damage may be caused when static electricity of ±200V or more is applied. Therefore, pay close attention to the operation and avoid touching the terminals with your hands.
4) In the case of soldering of the wire, solder the soldering iron to a temperature of 350°C or lower within 3 seconds. Soldering through solder baths may cause deterioration of performance, so please avoid them.
5) Please avoid cleaning the sensor. Otherwise, the cleaning solution intrudes into the lens and may cause deterioration of performance.