ST120 TO-5

ST120 TO-5 Detector circuit overlay

ST120 TO-5 Detector circuit overlay

ST120 TO-5 Thermopile Detector

ST120 TO-5 Thermopile Detector

A single-channel silicon-based thermopile provides lowest cost solutions in a small active area of 1.2mm x 1.2mm in a TO-5 package. Time constant of 25ms with Nitrogen encapsulation gas. Delivers a very low Temperature Coefficient of Responsivity of -0.04%/°C. This detector has a very short thermal shock response to ambient temperature change.

Excellent for gas analysis, fire suppression, non-contact temperature, and horizon sensor.

Low cost with high output.


  1. See Standard Windows and Filters (PDF) for list of optical filter options
  2. Internal 30kΩ 5% NTC chip thermistor provides ambient package temperature measurement. See DC-4005 section of Thermistor Options (PDF).
  3. Internal aperture precisely defines active area for applications with FOV and/or spot size requirements. See Aperture Options (PDF) for available sizes.
  4. See Thermopile Configuration Table for more options.

For more detailed information see the datasheet ST120 TO-5 (PDF).

Active Area size   1.2 x 1.2   AA mm Hot junction size, per element.
Element Area   1.44   A mm2  
Number of Junctions   80       Per element.
Number of Channels   1       Per detector package.
Output Voltage  150 190  230 Vs μV DC,  H=330μW/cm2 (3)
Signal-to-Noise Ratio  3,459 4,953  6,359 SNR √Hz DC, SNR=Vs/Vn
Responsivity  31.6 37.9  48.4 V/W DC, =Vs/HA  (2)
Resistance  80 90  115 R Detector element
Temperature Coefficient of   -.04     %/°C Best linear fit, 0° to 85°C (1)
Temperature Coefficient of  R   .02     %/°C Best fit, 0° to 85°C (1)
Noise Voltage  36.2 37.4  43.4 Vn nV/√Hz Vn2=4kTR
Noise Equivalent Power  .75 1.04  1.37 NEP nW/√Hz DC,  NEP= VnHA/Vs (2)
Detectivity  .87 1.15  1.61 D* 108√Hz/W DC,  D*=Vs/ VnH√A  (2)
Time Constant   25   Τ ms Chopped, -3dB point (1)
Field of View   61°/97°   FOV Degrees See Assembly Drawings for FOV Description.
Package Type   TO-5       Standard package hole size: Ø.150"
Operating Temperature -50   125 Ta °C  

General Specifications: 
Flat spectral response from 100nm to > 100µm.  Linear signal output from 10-6 to 0.1W/cm2
Maximum incident radiance 0.1W/cm2 , damage threshold ≥ .5W/cm2
(1) Parameter is not 100% tested. 90% of all units meet these specifications.
A is detector area in cm2.
Test Conditions: 500K Blackbody source; Detector active surface 10cm from 0.6513cm Diameter Blackbody Aperture.

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