1. Maximum Ratings (Any electrical stress that exceeds the parameters in the table below may cause permanent damage to the device.)
Parameter | symbol | Minimum | Maximum | unit | Note |
Voltage | Voo | -0.3 | 3.6 | V |
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Operating temperature | Tst | -20 | 85 | ℃ |
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pin limit | Into | -100 | 100 | mA |
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storage temperature | Tst | -40 | 125 | ℃ |
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2. Working conditions (T=25 °C, V DD = 3V, unless otherwise specified)
Parameter | symbol | Minimum | Typical | Maximum | unit | Note |
Voltage | VDD | 2.7 | 3 | 3.3 | V |
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operating current | IDD | 12 | 15 | 20 | μA |
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Sensitivity threshold | VSENS | 120 |
| 530 | μ V |
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Output REL |
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Output low frequency | LOL | 10 |
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| mA | VOL < 1V |
Output high frequency | LOH |
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| -10 | mA | VOH >（VDD-1V) |
REL low level output lock time | TOL |
| 2.3 |
| S | Not adjustable |
REL high output lock time | TOH | 2.3 |
| 4793 | S |
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Input SENS/ONTIME |
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Voltage input range |
| 0 |
| VDD | V | Adjustment range between 0V and 1/4VDD |
Input bias current |
| -1 |
| 1 | μA |
Enable OEN |
|
Input low voltage | VIL |
|
| 0.2 VDD | V | OEN voltage high to low threshold level |
Input high voltage | VIH | 0.4VDD |
|
| V | OEN voltage low to high threshold level |
Input Current | LI | -1 |
| 1 | μA | VSS < VIN < VDD |
Oscillator and filter |
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Low pass filter cutoff frequency |
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| 7 | Hz |
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High pass filter cutoff frequency |
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| 0.44 | Hz |
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Oscillator frequency on the chip | FCLK |
|
| 64 | KHz |
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3. Output voltage waveform
4.Output trigger mode
When the pyroelectric infrared signal received by the probe exceeds the trigger threshold inside the probe, a count pulse is generated internally. When the probe receives such a signal again, it will consider 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 received signal amplitude exceeds 5 times the trigger threshold, only one pulse is required to trigger the output of REL. The figure below shows an example of a trigger logic diagram. For multiple trigger situations, the hold time of the output REL is counted from the last valid pulse.
5. Extended time ONTIME
The voltage applied to the ONTIME terminal determines the delay time for the REL to maintain the high level output signal after the sensor is triggered. Each time the trigger signal is received, the delay time is restarted. Due to the dispersion of the internal oscillator frequency, the delay time. There will be a certain margin 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 grounding is the minimum threshold of voltage, the sensitivity is the highest. Any voltage above VDD/2 will select the maximum threshold, which is the lowest sensitive setting for PIR signal detection, ie the sensing distance may be minimal. It should be pointed out that the infrared sensor sensing distance is not linear with the SENS input voltage, and its distance is different from the signal-to-noise ratio of the sensor itself, the imaging object distance of the Fresnel lens, the background temperature of the moving human body, the ambient temperature, the environmental humidity, and the electromagnetic interference. Such factors form a complex multivariate relationship, that is, the output cannot be judged by a single indicator. In actual use, the result of the debugging is subject to change. The smaller the SENS pin voltage is, the higher the sensitivity is, the farther the sensing distance is. The S918-H has a total of 32 sensing distances, and the closest sensing distance can reach centimeter level. In actual use, the resistance division method can be used to achieve the adjustment sensitivity.
