How to Graph Diode Reverse Characteristics

Engineers and technicians often need to graph reverse diode characteristics, charting the voltage across a diode versus the current through the diode. Engineers and technicians use the graph to determine the amount of reverse current that will flow through a diode at a specific reverse voltage level and to determine the maximum reverse voltage that can be applied before the diode breaks. Although in many applications the maximum reverse voltage rating would never be exceeded, some applications will require that the diode withstand a reverse voltage of well over 50 volts.

Things You'll Need

  • 10-square-per-inch graph paper
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Instructions

    • 1

      Obtain a table of current values for specific reverse biased voltage levels from direct measurements or lab data presented to you.

    • 2

      Find the minimum and maximum voltage level used in the table. Subtract the maximum value minus the minimum value and divide the result by the number of horizontal grid marks on your graph paper. Name this number "voltage per horizontal grid mark."

    • 3

      Find the minimum and maximum current level recorded in the table. Subtract the maximum value minus the minimum value and divide the result by the number of vertical grid marks on your graph paper. Name this number "current per vertical grid mark."

    • 4

      Find the grid intersection point that is at the intersection of the lowest horizontal grid line at the leftmost vertical line on the graph paper. Call this intersection point the "maximum power point." Label this point with the the voltage and current coordinates that correspond to the lowest voltage level and the lowest current level listed in the table (the reverse diode characteristics will exhibit the highest reverse current when the reverse voltage is highest and the lowest reverse current when the reverse voltage is lowest). Call the lowest horizontal grid line the "base line."

    • 5

      Label each consecutive grid mark on the base line in increments that correspond to the "voltage per horizontal grid mark" such that each horizontal grid mark to the right of the first grid mark will have a successively lower voltage value. Repeat until you reach the minimum voltage level on the table (most often 0 Volts).

    • 6

      Construct a vertical line through the "maximum power point" that extends the length of the paper. Label each consecutive grid mark on the vertical axis in increments that correspond to the "current per horizontal grid mark" such that each vertical grid mark will have a successively lower current value than the "maximum power point." Repeat until you reach the the minimum current level in the table (most often 0 milliamperes).

    • 7

      Plot each of the voltage-current coordinate pairs that are in the table on the graph. After each point has been plotted, connect the points together with lines starting at the "maximum power point" and connecting to the next point that is the first point directly to the right.

    • 8

      Draw the horizontal and vertical axis of the graph using the point that corresponds to 0 Volts and 0 milliamperes on the graph paper.

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