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Just two things to observe: Ohm's law and the maximum current the output of the IDAC may deliver/sink.
What voltages would you like to have?
Bob
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There is an internal resistance for the switch to connect the IDAC to the pin. In the .cydwr view choose the "Analog" tab. With a lright-click on your IDAC you may select the ohm meter. When clicking on the pin you will see a resistance of ~200Ohms. Take that into your shunt calculation. So a shunt of ~ 6.2k will give you ~2V if I am not mistaken.
Bob
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Even when you use a zero-ohm resistor the current will be not more than what the IDAC is programmed to, Only when R is too high, the volatge will reach its max before the required current can flow.
Look at IDAC datasheet for variance of I over the voltages. Comparably stable output of I.
Bob
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Keep in mind a current source has a limiting R value due to its
necessary limit on complience. That is there is some min V required
across the current source to keep it in its active region regulating
current.
On the low R size no limits per se but then route and pcb parasitics
come into play.
Regards, Dana.