The **IRS-B210ST01-R1** is a high-sensitivity, dual-element surface-mount (SMD) **Pyroelectric Infrared (PIR) Sensor** manufactured by Murata. It is primarily used for human detection by sensing moving thermal radiation. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical and physical characteristics: | Parameter | Specification | | :--- | :--- | | **Type** | Dual Element (Balanced) | | **Supply Voltage** | 2.0V to 15.0V | | **Field of View** | 120° (Horizontal) x 100° (Vertical) | | **Output Type** | Analog (Voltage) | | **Package Type** | Surface Mount Device (SMD) | | **Operating Temperature** | -40°C to +70°C | | **Dimensions** | 5.0 x 4.7 x 2.4 mm | --- ### 2. Internal Components & Structure The sensor is not a single component but an integrated package containing: 1. **Pyroelectric Ceramics:** Two sensing elements (Dual Element) are connected in series-opposition. This design allows the sensor to cancel out background noise and signals caused by ambient temperature changes, triggering only when a "heat source" moves across the elements. 2. **Infrared Filter:** A silicon-based optical window that filters out visible light, allowing only infrared wavelengths (typically 5–14µm) to pass through. 3. **Field Effect Transistor (FET):** An internal FET acts as an impedance converter. Since the pyroelectric ceramic produces a very high-impedance signal, the FET converts it into a low-impedance voltage output suitable for processing by an MCU or Op-Amp. --- ### 3. Application Circuit Components To use the IRS-B210ST01-R1 in a real-world design, you typically need the following external parts: * **Fresnel Lens:** Essential for focusing IR energy onto the small sensor surface and extending the detection range. * **Operational Amplifiers (Op-Amps):** The raw output is very small (millivolts). Two stages of amplification with a band-pass filter (0.3Hz to 10Hz) are usually required. * **Voltage Regulator:** A stable, low-noise power supply is critical, as PIR sensors are highly sensitive to power ripples. --- ### 4. Advantages of this Model * **SMD Form Factor:** Unlike traditional TO-5 metal can PIR sensors, this "ST" version is reflow-solderable, enabling thinner and more compact PCB designs. * **High SNR:** Murata’s ceramic technology provides a high signal-to-noise ratio, reducing false triggers in smart home applications.