Posted on Jan 6, 2013 6320
This circuit uses the +5 V reference output and the op amp to level shift and amplify the 2.1 mV/Â°C Tempco output into a voltage signal dependent on the ambient temperature. Different scaling can be obtained by selecting appropriate resistors from the table giving output slopes calibrated in degrees Celsius or degrees Fahrenheit. To calibrate, first measure the voltage on the Tempco pin, VTEMPCO. and the ambient room temperature, TA in Â°C.
Where S = Scale factor for your circuit selected from the table in mV. Then turn the circuit power off, short VouT at pin 6 of the REF-02 to ground, and while applying exactly 100.00 mV to the op amp output, adjust R82 to that V8 = (X) (100 mV). Now remove the short and the 100-mV source, reapply circuit power and adjust Rp so that the op-amp output voltage equals (7A) (S). The system is now exactly calibrated.