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Temperature sensors

Smartec SMT130-60

This temperature sensor has a output frequency of 1kHz - 6 kHz. The temperature information is however contained in the duty cycle of the signal. This has some special properties:

  • The average of the signal (after RC low pass filtering) results to a voltage proportional to the temperature.
  • Random sampling using f.i. the RS232 port of a PC followed by averaging in software also results to the temperature
  • The output signal is CMOS/TTL compatible. This enables it to by multiplexed with the output of several (hundreds) of sensors at low cost.
  • The output signal can be connected directly to any microcontroller. Further signal conditioning is not required.
  • Averaging of successive duty cycles improves the resolution with virtually no limit. In one application a resolution of 0.002 ºC has been realized. This way it has been possible to detect the growth of bacteria in milk cartons.
  • The temperature range of the sensor is -45ºC tot +135ºC which is exceptionally large for an IC sensor, thanks in part to the duty cycle shaped signal.