\tcolorbox with Equation and \footnotetext

Question

I need help on is with \tcolorbox.

I have two equations but I need only one \footnotetext.

How to proceed?

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[most]{tcolorbox}
\begin{document}
    
\begin{tcolorbox}[title=CORREÇÃO]
    A equação da corrente no emissor de $Q_1$ e $Q_2$, com $V_{BE} = V_B - V_E$     
    
    \begin{align*}
    \tcbhighmath{ I_{E_1} = \dfrac{I_S}{\infty} \, e^{\dfrac{(V_{B_1} - V_E)}{V_t}}   }      \qquad
    \tcbhighmath{ I_{E_2} = \dfrac{I_S}{\infty} \, e^{\dfrac{(V_{B_2} - V_E)}{V_t}}   }
    \footnotetext{Video Aula 3C, Slide 17, 9:50 minutos}
    \end{align*}
    
    Dividindo $I_{E_1}$ por $I_{E_2}$ e vice-versa:
    
\end{tcolorbox}

\end{document}

Image 1 is the current result. Image 2 is what I need.

You have no idea how much I appreciate all of this.

And thank you very much for your cooperation.

Answer 1

As I commented, remove the \footnotetext macro from the align* environment, because it performs a multiple-pass, grabbing the \footnotetext on each pass.

Please let me know if I misunderstand your need.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[most]{tcolorbox}
\begin{document}
    
\begin{tcolorbox}[title=CORREÇÃO]
    A equação da corrente no emissor de $Q_1$ e $Q_2$, com $V_{BE} = V_B - V_E$     
    
    \begin{align*}
    \tcbhighmath{ I_{E_1} = \dfrac{I_S}{\infty} \, e^{\dfrac{(V_{B_1} - V_E)}{V_t}}   }      \qquad
    \tcbhighmath{ I_{E_2} = \dfrac{I_S}{\infty} \, e^{\dfrac{(V_{B_2} - V_E)}{V_t}}   }
    \end{align*}
    \footnotetext{Video Aula 3C, Slide 17, 9:50 minutos}
    
    Dividindo $I_{E_1}$ por $I_{E_2}$ e vice-versa:
    
\end{tcolorbox}

\end{document}

If your goal (I'm trying to understand the red arrows in the OP figures) is to place the footnote in the tcolorbox itself, I would instead fudge it, as I do below using stacks. In the left box, I use a \tiny footnote size, and in the right box, I use \scriptsize.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[most]{tcolorbox}
\usepackage[usestackEOL]{stackengine}
\stackMath
\begin{document}
    
\begin{tcolorbox}[title=CORREÇÃO]
    A equação da corrente no emissor de $Q_1$ e $Q_2$, com $V_{BE} = V_B - V_E$     
    
    \begin{align*}
    \tcbhighmath{ \Shortunderstack[l]{%
    I_{E_1} = \dfrac{I_S}{\infty} \, e^{\dfrac{(V_{B_1} - V_E)}{V_t}}\\\\
    \rule{4em}{.6pt}\\\text{\tiny Video Aula 3C, Slide 17, 9:50 minutos}}} 
    \qquad
    \tcbhighmath{ \Shortunderstack[l]{%
    I_{E_2} = \dfrac{I_S}{\infty} \, e^{\dfrac{(V_{B_2} - V_E)}{V_t}}\\\\
    \rule{4em}{.6pt}\\\text{\scriptsize Video Aula 3C, Slide 17,}\\
    \text{\scriptsize 9:50 minutos}}} 
    \end{align*}
    
    Dividindo $I_{E_1}$ por $I_{E_2}$ e vice-versa:
    
\end{tcolorbox}

\end{document}