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Infrared Thermometer | Cypress Semiconductor

Block Diagram

Design Considerations

Infrared thermometers are widely used in Industrial and Medical application to measure object or patient temperature without contact. Apart from being a more hygienic option Infrared thermometers have a much wider range for temperature measurement and have accuracies comparable with traditional liquid-metal thermometers.

An Infrared thermometer uses a thermopile sensor to measure temperature. Thermopile sensor has an IR absorber which is connected to a series of thermocouples which measure the object temperature. The ambient temperature of the sensor is measured using a thermistor.

The basic steps used to calculate temperature are 1) to measure the thermopile voltage and 2) measure the thermistor resistance (to calculate the ambient temperature) which is compensated to arrive at the final object temperature.  

Usually the output of a thermopile is in the order of a few µV which has to be amplified. Using Correlated Double Sampling the output can be amplified while reducing undesired offset and low frequency noise. An Infinite Impulse Response (IIR) filter can be used to reduce high frequency noise. This conditioned output can finally be used for calculating the object temperature reading from the thermopile.

PSoC ® 3’s wide operating voltage range of 0.5V to 5V, low active current of 1mA @ 6 MHz, sleep current of 1µA and hibernate current of 200 nA makes it an ideal choice for a one-chip Infrared thermometer solution.

Software and Drivers

  • PSoC Creator

    PSoC Creator is a state-of-the-art software development IDE combined with a revolutionary graphical design editor to form a uniquely powerful hardware/software co-design environment.

  • PSoC Designer

    PSoC Designer is the revolutionary Integrated Design Environment (IDE) that you can use to customize PSoC to meet your specific application requirements. PSoC Designer software accelerates system bring-up and time-to-market.