Hi everyone,
I'm using OPA549 to compensate voltage drop due to internal and external resistance of a current source (Ri in the schematic, around 20 mohm) based on the circuit schematic below. The current passing through the load can be up to 10 A, so I chose OPA549 (the op-amp with very high output/sink current). The circuit kind of worked (Voltage different between A and B kept almost 0 and unchanged, this is necessary for my application) for low currents (<0.6A), but it would not work at higher current, which might be due to thermal shutdown according to the datasheet. I'm getting a better heat sink, but by passing current of 10A (or 8A continuously), the power dissipation would be more than 40 W (I'm using a +/- 5V power supply), and it is difficult to find heat sink so powerful and with acceptable price. So I was wondering if I can get some help here about the circuit improvement. Are there better methods for voltage compensation? If not, is there any good method to mitigate the heat dissipation problem? Thanks a lot!
3252.Voltage compensation using OPA 549.tif
More information about how the circuit works can be found from http://www.circuit-fantasia.com/circuit_stories/inventing_circuits/ser_nr_comp/ser_neg_res_comp.htm