IR sensors detect infrared radiation for non-contact sensing. Our catalog spans two distinct technology paths: pyroelectric (PIR) human-presence sensors — leading parts like M8601 and M9601 are digitally programmable, so the same chip can switch between a Motion mode (direct I/O-level presence decision) and a Digital mode (raw PIR signal plus temperature output) rather than being locked into one output; and thermopile sensors — array-type or single-point bare-die — which always output raw signal data for the host to process. The two operate on different principles, so the first step is identifying which category the application needs.
Reading the Key Parameters
- VDD (supply voltage): single-point PIR parts in our catalog cover 1.4V to 3.6V, while array-type thermopile signal-conditioning chips (e.g. 1x8 and 1x32 arrays) cover 2.7V to 3.6V. The wide voltage range suits battery power or direct connection to a system rail — check whether the minimum voltage covers the battery's end-of-discharge point.
- IDD (supply current): PIR parts can draw as little as 3.0µA to 4.5µA, suited to battery-powered, long-duration presence sensing. Array-type thermopile chips, which must drive array readout circuitry, draw roughly 5mA — a markedly different power profile from single-point PIR.
- Output mode: most PIR parts are digitally programmable — per the key_params for M8601 and M9601, the same chip can switch between a Motion mode (direct I/O-level decision) and a Digital mode (raw PIR signal plus temperature value, read over single-wire/I2C), not split across separate part numbers by output type. Thermopile parts (array-type or single-point bare-die) output raw signal only for host-side computation, with no I/O decision mode. Confirm which mode combination a given part actually supports before selecting.
- Package: catalog parts are mostly DFN8L2X2-0.55 or bare die, typically requiring secondary packaging or an optical window/filter — evaluate the optical design and assembly-line mounting capability together with part selection.
Three Steps to Select
- Determine whether the application needs presence/motion detection or non-contact temperature sensing — the former points to PIR digital-output parts, the latter to thermopile raw-signal parts.
- Check VDD/IDD against battery capacity or system power-supply design.
- Evaluate mounting process and optical-window design difficulty based on package form (bare die/DFN), confirming feasibility with mechanical engineering where needed.
Common Pitfalls
- Confusing PIR presence sensing with thermopile non-contact temperature sensing — choosing the wrong category causes complete functional mismatch.
- Sizing only against static IDD while ignoring transient current during self-test or digital-output modes, which affects battery design.
- Costing bare-die parts as if they were finished packaged chips, overlooking the added packaging and wire-bonding process cost.
Use the online selector to filter and compare part numbers against the ranges above; for engineering support, reach our engineers via a part-number inquiry.