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Difference between revisions of "diode"

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The above can be expressed as a step function.
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I_D =
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  0, & V_D\leq 0 \\
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[[Category:electronic components]]
 
[[Category:electronic components]]

Latest revision as of 01:39, 6 August 2018

A diode is a two-terminal electronic device that permits the flow of current primarily in one direction.

Overview[edit]

A diode is a two-terminal electronic device that allows current to flow in just one direction. When flowing in the forward-biased direction, the diode acts as a wire with very low resistance, creating a short-like condition. Attempting flow in the reverse-biased direction will result in a very high resistance, prohibiting the flow of current, creating an open circuit condition.

Ideal Diode[edit]

The current-voltage characteristic of an ideal diode is shown below.

ideal diode i-v.svg

The forward resistance ( Equation upper R Subscript f ) of the ideal diode can be obtained through Ohm's law where the forward voltage ( Equation upper V Subscript f ) across the diode is 0 (given from the I-V curve above) and the forward current ( Equation upper I Subscript f ) is any amount of current.


Equation upper R Subscript f Baseline equals StartFraction upper V Subscript f Baseline Over upper I Subscript f Baseline EndFraction equals StartFraction 0 upper V Over Any positive current left-parenthesis e period g period comma 5 mA right-parenthesis EndFraction equals 0 normal upper Omega


When conducting, an ideal diode acts as a wire with 0 Ω of resistance. In other words, in the forward-biased direction, an ideal diode is a short circuit.

ideal diode forward biased.svg

For the reverse-biased resistance ( Equation upper R Subscript f ), the reverse voltage ( Equation upper V Subscript r ) across the diode is any negative value and the reverse current ( Equation upper I Subscript r ) is 0.


Equation upper R Subscript r Baseline equals StartFraction upper V Subscript r Baseline Over upper I Subscript r Baseline EndFraction equals StartFraction Any negative voltage left-parenthesis e period g period comma hyphen 1.5 upper V right-parenthesis Over 0 mA EndFraction equals normal infinity normal upper Omega

When resisting, an ideal diode acts as a wire with ∞ Ω of resistance. In other words, in the reverse-biased direction, an ideal diode is an open circuit.

ideal diode reverse biased.svg

The above can be expressed as a step function.

Equation upper I Subscript upper D Baseline equals StartLayout Enlarged left-brace 1st Row 1st Column 0 comma 2nd Column upper V Subscript upper D Baseline less-than-or-equal-to 0 2nd Row 1st Column normal infinity comma 2nd Column upper V Subscript upper D Baseline greater-than 0 EndLayout


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