constant current TC
Posted 04 September 2012 - 03:49 PM
Posted 04 September 2012 - 04:22 PM
Posted 04 September 2012 - 10:44 PM
The x-axis is the temperature of the current source. That is, the temperature of the U6. So if you keep the U6 at around 30 degrees C, you can expect the tempco of the current source to be about -20 PPM/degC. This gives you an idea of how much a few degrees of temperature change to the U6 will affect the output of the current source.
If you use the precision resistor mentioned earlier in Section 2.5, you don't have to worry about tempco because you will be measuring the actual current in real time. If the U6 temperature is changing greatly, though, you do have to worry about tempco effects on the analog inputs themselves.
I expect the temperature to rise to 40 degc, any idea what the tc is for the analog inputs?
Posted 05 September 2012 - 07:36 AM
If this sort of tempco is significant in your system, I suggest you determine the actual tempco of your U6 in the desired region of operation, and then include that in your calculations. One good way to measure tempco is to have a fixed voltage source at steady temperature, and connect that to an analog input on a U6 where temperature is varied.
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