voltage controlled current source design

I need a vccs with input range of 0-5V and output current range of 0-5A.
Can I use two op-amps with a BJT in the feedback path which is suggested by some website?
What are the main considerations in the VCCS design? If the above topology is ok, what are the requirements of the op-amp and BJT?

Thank you very much.

Please post the schematic.

It sounds like a good way of doing it.

wtwendy said:

I need a vccs with input range of 0-5V and output current range of 0-5A.
Can I use two op-amps with a BJT in the feedback path which is suggested by some website?
What are the main considerations in the VCCS design? If the above topology is ok, what are the requirements of the op-amp and BJT?

Thank you very much.

Click to expand...

Look at this previous post.

You might want to add an amplifier on the sense resistor so you can limit the drop-out voltage.

If you use a 100mΩ resistor for the sense, an op-amp with a gain of 10 would enable you to use it for 0-5V to 0 to 5A conversion with a maximum voltage loss of 0.5V.

For higher currents I'd definitely go with Hero's suggestion of an extra opamp so you can keep the sense resistor small. Aside from wasting less power as heat the lower heat in the sense resistor means it will be more linear, big sense resistors will also drop a lot of voltage so the whole circuit will be effectively DC biased above ground.