Excelitas' infrared sensing technologies are playing a vital role in creating a healthier, safer and cleaner tomorrow. We have gained worldwide recognition for the design and production of our thermopile array modules.
These arrays include detectors composed of several thermocouples typically connected in series. They are DC-type detectors and, thus, best suited for non-contact temperature measurement. Our thermopile modules are based on silicon micromachining technology. A special IR-absorption layer covers the hot junctions, creating the sensor’s sensitive area.
Thermopile linear arrays with digital interface consist of a thermopile line/matrix array sensor with integrated ASIC, E2PROM, a microcontroller with integrated 10-bit analog-to digital converter for signal processing and interfacing.
The microcontroller controls the multiplexer of the thermopile line/matrix sensor as well as all internal operations. These include measurements and calculations for the object, ambient temperatures and post-processing of the temperatures to output them via a digital serial interface (SMBus). The temperature-dependant signal of the thermopile line array elements is subsequently fed through an analog-input multiplexer into a low noise, low offset chopper amplifier with constant gain. The amplified thermopile signal, a voltage reference signal and the signal from the on-chip integrated PTAT (ambient temperature) sensor is connected to an output multiplexer which alternately feeds the signals to the analog digital converter (ADC) of the microcontroller.
After analog-to-digital conversion, the resulting digitized voltage signals are stored in the microcontroller’s RAM. Based on the calibration settings stored in the TPLM’s E2PROM and on the described measurement results, ambient temperature voltage signal (VTamb) and normalized voltage signals for individual pixels (Pi) are calculated from the raw signals.
An SMBus-compatible, two wire bidirectional serial interface is provided to read out the sensor’s temperature signals and for Read/Write access to the sensor’s configuration data and calibration parameters. The SMBUS allows connection of a master device (MD) and one or more slave devices (SD).