Introduction
A PIR sensor datasheet contains all the technical information you need to use the sensor correctly. But if you’re new, the jargon can be overwhelming. This guide explains common sections and parameters.
Typical Sections of a PIR Sensor Datasheet
1. Features and Applications
This section summarizes what the sensor does and where it’s used. Look for key phrases like “low power,” “digital output,” “motion detection.” It gives a quick overview.
2. Absolute Maximum Ratings
These are limits you must never exceed (voltage, temperature, etc.). Exceeding them can destroy the sensor. Always operate well within these limits.
3. Electrical Characteristics
The most important section. Common parameters:
- Supply voltage (VDD): The allowed power voltage range.
- Supply current (IDD): How much current the sensor draws. Crucial for battery projects.
- Output voltage (VOH, VOL): HIGH and LOW output levels. Important for logic compatibility.
- Response time / delay: How long output stays HIGH.
- Sensitivity / detection range: Maximum distance (often with a specific lens).
- Field of view: Detection angle.
4. Timing Diagrams
Graphs showing how the output behaves over time. Look for warm-up time, hold time, and block time.
5. Mechanical Dimensions
Physical size and pin spacing. Useful for PCB layout or enclosure design.
6. Application Information
Sometimes includes example circuits, lens selection, and mounting guidelines.
Key Parameters to Focus On
- Operating voltage: Is it compatible with your microcontroller?
- Output type: Digital, analog, open-drain? Open-drain needs a pull-up.
- Current consumption: For battery life.
- Detection range: Under what conditions? (often with a specific lens).
- Warm-up time: How long after power-up until stable.
- Operating temperature: For outdoor use.
Example: HC-SR501 Datasheet (Typical)
While HC-SR501 is a module, not a bare sensor, many online “datasheets” exist. They often list:
- Voltage: DC 4.5-20V
- Current: <50mA (but standby is much lower)
- Output: 3.3V HIGH, 0V LOW
- Range: 3-7m adjustable
- Delay: 5-200s adjustable
- Warm-up: ~1 minute
Where to Find Reliable Datasheets
- Manufacturer websites (Panasonic, Murata, Excelitas)
- Distributor sites (DigiKey, Mouser) often have links
- For modules like HC-SR501, be cautious – many are community-sourced and may not be accurate.
Conclusion
Learning to read datasheets is a key skill. Focus on the electrical characteristics and timing, and you’ll avoid many common mistakes.