I am working on a multi-range current source using APEX MP38 OpAmp to generate and force-in either 100mA or 2A into a mainly resistive load. I came across Howland Current Pump configuration and I hope that its going to work, but the preliminary simulation using LTSpice fails miserably.
The resistive load that I am dealing with changes its resistance greatly due to environment temperature and the temperature induced by the current. Using discrete current sources I have observed that at room temp (25°), the resistance of this load is 20Ω and at 180° its 60Ω.
Now I want to have a current source that can output 100mA or 2A using a switch. Something like:
So my question is, can you please let me know if MP38 is a good candidate for this task? What kind of opamp I should use as the voltage follower (U2). Any ideas about input/feedback resistor values and their wattage? let me know if there is some information missing!