How to generate current from PXI-6238

[sriveni]

Hi,

I am using PXI-6238 for current measurement and generation. From the specification document the figure shows as connecting the Power supply and User Load should be able to generate the current.  Reading at the output specifications, it says the internal voltage drop is 3v max with respect to external power supplied. Suppose if I connect 10VDC and load of 250 Ohms, the voltage drop across the load resistance when generating 20mA is 5V. Considering the internal voltage drop and voltage drop across the resistance, the total voltage drop is not equal to the external power supplied. I was thinking this could damage the device.

Can anyone suggest what will the voltage supply I have to use and load resistance to be connected to generate 0-20mA current.

Thanks in advance.

[Henrik_Volkers]

The spec is not so well written.... it should note  the MINIMUM internal voltage drop, which is noted to be 3V max 🙂

Since you apply a (more or less) constant voltage, and you want a controlled current in your load resistor, the device will act like a variable resistor, always set to  a value such that the set current is flowing.

So your setup with a 10 V source and a 250 Ohm load will not harm the device and should run, 250 Ohm and 20mA will give you 5V , plus the 3V the current regulator needs results in about 2V left for regulation.