  \centerline{%
    \begin{tikzpicture}[scale=1.4,>=latex]
      \fill[gray!30] (0,0) -- (0,0.28) -- (0.224,0);
      \fill[gray!30] (4,0) -- (1.6,0) -- (1.6,0.48) -- (4.0,0.48);
      \fill[gray!60] (0.224,0) -- (1.6,-1.72) -- (1.6,0);
      \draw (0,0.48) -- (0,0.28) -- (1.6,-1.72) -- (1.6,0.48) -- (4,0.48) -- (4,0.28);
      % horizontal axis
      \draw[->] (-0.2,0) -- (0.5+4,0) node[right] {$t$};
      \draw (0.224,0.0) -- (0.224,-0.1) node[below] {$T_x$};
      \draw (1.6,0.48) -- (1.6,0.48) node[above] {$T_1$};
      \draw (4.0,0.0) -- (4.0,-0.1) node[below] {$T_s$};
      % vertical axis
      \draw[->] (0,-1.8) -- (0,0.7) node[above] {$i_{C_{in}}(t)$};
      \draw (0,0.48) -- (-0.1,0.48);
      \draw[<-] (-0.3,0.53) -- (-0.7,0.68);
      \node[left] at (-0.7,0.8) {$I_{in}$};
      \draw (0,0.28) -- (-0.1,0.28);
      \draw[<-] (-0.3,0.25) -- (-0.7,0.08) node[left] {$i_1 = I_{in} - \min i_L$};
      \draw (0,-1.72) -- (-0.1,-1.72) node[left] {$i_2 = I_{in} - \max i_L$};
%      \node at (2.0,-3.5) {$\text{I: } \min i_L < I_{in}$};
    \end{tikzpicture}
  }
