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The TSD Series includes an infrared sensor and a sensor signal conditioner.
digital thermopile sensors


  • 0°C … up to +300°C measurement ranges
  • Small size
  • Small field of view available
  • Up to ±1°C accuracy
  • I2C Interface
  • Low current consumption
  • Operating temperature range: -10°C to +85°C


  • Contactless temperature measurement
  • Climate control
  • Industrial process control
  • Household applications


Frequently Asked Questions

What are my considerations for the “Field of View” for a thermopile sensor?
The thermopile’s field of view must be directed to the object surface of interest. The distance to the surface or the surface diameter must be adjusted to ensure that the complete sensors field of view is covered by the object, see example on the left in the picture below. Refer to the datasheet for distance minimums and minimum diameters by part number.


Does sunlight impact thermopile accuracy?
Sun light radiation which is transmitted through a glass window may influence the measurement accuracy. To avoid this, the thermopile sensor is equipped with a long wavelength filter. Due to not ideal filter characteristics a small portion of radiation will be added to the radiation of the object. In case of direct sunlight exposure this error can be up to +0.2°C.


Is the sensor cap sensitive?
Users should avoid touching the sensors cap. There will still be a measurement deviation after changing the sensors temperature rapidly.


Are there special cleaning instructions?

Recommended cleaning:

  • Isopropanol (other names: Iso-Propyl-Acohol (IPA), 2-Propanol),
    use medical grade, pro analysis grade or purer
  • Scratch and lint free cleaning tissue (e.g. Bemcot M-3II)

Using the wet tissue:
Clean from the center of the window or lens to the outside. Take care that you also clean the tiny step between optics and metal case of the thermopile properly.

  • Check for stains after wet cleaning, if necessary repeat the wet cleaning.
  • Check for lint after wet cleaning; if necessary wipe lint with a dry tissue. 
  • Please Note: Some Q-tips have the cotton attached to the stick with glue. In some cases this glue is dissolved by the isopropanol and leaves a deposit on the optics. Due the infrared absorption of this deposit the calibration may be compromised.


What is emissivity as it relates to thermopiles?
Every object is transmitting infrared energy in dependence to its temperature. The emissivity is the ratio of the radiated power by an object to the radiation of an ideal black body. Common materials like liquids, clothes, human skin, foods have emissivity factors >0.90 and therefore they can be measured very accurately without adopting the sensors specification. Refer to the datasheet to understand how to compensate the measurement for an object with significantly low emissivity.


Do the TSD thermopiles feature EMC protection? Yes, to a certain voltage ±2V (Human Body Model). Due to the use of these modules for OEM application no CE declaration is done. Especially line coupled disturbances like surge, burst, HF etc. cannot be removed by the module due to the small board area and low price feature. There is no protection circuit against reverse polarity or over voltage implemented. The module will be designed using capacitors for blocking and ground plane areas in order to prevent wireless coupled disturbances as good as possible.


Please review product documents or contact us for the latest agency approval information.  

Product Type Features

  • Model Number  TSD305-1C55, TSD305-1SL10, TSD305-2C55, TSD305-3C55

  • Sensor Type  Digital Thermopile Component

Electrical Characteristics

  • Supply Voltage (V) 1.68 – 3.6

Body Features

  • Filter  Blank Silicon Lens, Long Wave Pass 5.5µm

Termination Features

  • Wire/Cladding/Connection  Metal Pin


  • Diameter (mm) 9.1

  • Diameter (in) 32 – 212, 32 – 572

  • Length (mm) 4.4, 8.45

  • Length (in) .17, .33

  • Wire Length (mm) 13.2, 13.5

  • Wire Length (in) .52, .53

Usage Conditions

  • Ambient Temperature Range  -20 – 85 °C [ -4 – 185 °F ]

  • Object Temp. Accuracy (°C) ± 1, ± 4.5

  • Object Temperature Range (°C) 0 – 100, 0 – 300

  • Object Temperature Range (°F) 32 – 212, 32 – 572


  • Output/Span Resolution (°C) .1

  • Output Interface  I2C

Packaging Features

  • Package  TO-5


  • Pixel Type  OEM Module, Single Pixel

  • Optics  Flat Window, Silicon Lens

Related Materials

Datasheets & Catalog Pages

Terms and Conditions

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This information has been provided to your free of charge for your use but remains the sole property of TE Connectivity Corporation (''TE'') or SnapEDA,  Inc. or Ultra Librarian/EMA Design Automation, Inc. (collectively, "Company"). While Company has used reasonable efforts to ensure its accuracy, Company does not guarantee that it is error-free, not makes any other representation, warranty, or guarantee that the information is completely accurate or up-to-date. In many cases, the CAD data has been simplified to remove proprietary detail while maintaining critical interface geometric detail for use by customers. Company expressly disclaims all implied warranties regarding this information, including but not limited to any implied warranties or merchantability or fitness for a particular purpose.