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OPA541: Howland Current Pump for Helmholtz coil

Yuchao Chen
Prodigy 10 points
Part Number: OPA541
Other Parts Discussed in Thread: OPA549

Hi,

I'm trying to build a current drive for Helmholtz coil following the designs in ieeexplore.ieee.org/.../8822683

To obtain higher current, I plan to use OPA541 in place of LM657. Are there any potential issues for using OPA541 in this circuit? Is there a better op amp to use here to achieve high voltage (30V) and current (>5A)? Thanks!

  • +1
    TI__Guru 62300 points

    OPA541 is a good choice to meet your high +/-30V voltage supplies and output current (>5A) needs.  The only other part that I am aware to be able to meet these requirements is OPA549.

  • 0 in reply to Marek Lis
    Prodigy 10 points

    Hi Marek, I built the circuit but found the output to be independent of the input voltage Vi.

    Here are some measured voltages:

    V- = 1.3  V

    V+ = 1.1 V 

    Vo = 14 V

    Io = 2A

    Would the above indicate that the op-amp is damaged? Thanks!

    Best,

    Yuchao.

  • 0 in reply to Yuchao Chen
    TI__Guru 62300 points

    What are V- and V+?  I hope these are NOT supply voltages since the minimum supply for OPA541 is 20V (or +/-10V) and the minimum supply voltage for OPA549 is 8V (or +/-4V). If you need further assistance, a picture is worth thousand word - please attached circuit simulation schematic by clicking on INSERT button below the active window.

  • 0 in reply to Marek Lis
    TI__Guru 62300 points

    I'll close this thread for now.  If you need further assistance, please reply or start a new E2E inquiry.