\documentclass[]{standalone}
\input{./tikzpreamble}

\begin{document}
\begin{circuitikz}[scale=2]
    \draw[color=black, thick]
    (1,0) 
        to [R, text width=1cm, l={R 500$\mu$},f>^=I$_{IN}$,  *-] (1,3)
        to [short, -o] (0,3) node[left] {V$_{IN} = -48V$}

    (1,3) node[draw=black, fill=white, regular polygon, regular polygon sides=4] {PowerIt}
    (.52, 3) node[right, draw=black, inner sep = 2] {-}
    (1,2.52) node[above, draw=black, inner sep = 1] {+}

    (1,3) to [short, -*] (1,2.52)
    (1,3) to [short, -*] (.52, 3)

    (0,0) node[left]{GND$_{-48V}$} to [short, o-] (1,0)

    (2.5,1.5) node[fd op amp] (fdoa) {}
    (fdoa.+) to [short,-*] (1,1.0)
    (fdoa.-) to [short,-*] (1,2.0)
    (fdoa.down) 
        to (2.46,0)
        to [short,-o] (6,0) node[right]{GND$_{3.3V}$}
    (fdoa.down)+(-.2,-.1) 
        to (2.26,0)
        to [short, -*](1,0)
    (fdoa.up) 
        to (2.46,3)
        to [short,-o](6,3) node[right] {$V_{SS} = 3.3V$}
    (fdoa.up)+(-.2,.1)
        to (2.26,2.2)
        to (.3, 2.2)
        to [short, -*] (.3,3)
    
    (4.5,1.5) node[op amp] (oa) {}
    (fdoa.out -) to (oa.-)
    (fdoa.out +) to (oa.+)

    (5,0) node[ground]{} node[circ](4.5,0){}

    (oa.up) to [short, -*] (4.46, 3)
    (oa.down) to [short, -*] (4.46, 0)
    (oa.out) to [short,-] (5.5,1.5) node[right,draw=black] {MONITOR\_48I}
    
    ; 
\end{circuitikz}
\end{document}