I have an analogue problem which I hope someone can push a hardware-challenged software person (me) in the right direction :)
What I need to do is precisely set control the amount of current flowing through a coil from software (it generates a magnetic field). I figure a DAC controlled current source of some description is the best option. Nominal coil resistance is 10-20 Ohms with a horrible tempco (3000 ppm/degC, apparently).
The current must be able to flow both ways from -25mA to 25mA.
Ideally, I'd like a single supply to do this, as I already have a clean +5V rail. Any other rails I would need to generate.
The best solution I have managed to dig up so far is a DAC controlling a Howland Current Pump, but requires dual supplies (and, from what I gather, +/-15V supplies for the +/- 25mA current).
Since the coil doesn't need to have one end connected to ground, I'm wondering if there are any better options - say, with the load as part of a feedback loop or bridge arrangement.
Is there a op-amp topology that I should look at that might do the job?