Free · Physics models
Ideal Shockley Diode Current
Solve diode current or a compatible voltage and model parameter using the exponential junction equation.
- Formula & worked example
- Private in your browser
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Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
With Is = 1 mA, n = 1 and Vt = 25 mV, Vd = 25 mV gives about 1.71828 mA.
I = Is [exp(Vd/(n Vt)) − 1].
Worked example
Enter these known values and leave the other values blank.
- Emission coefficient (n)
- 1
- Saturation current (I==S==)
- 1 mA
- Thermal voltage (V==T==)
- 0.025 V
- Voltage drop (V==D==)
- 0.025 V
- Current (I)
- 1.7183 mA
Assumptions and limitations
- The model describes an ideal junction without series resistance, high-current effects or reverse breakdown.
- Saturation current and thermal voltage are positive, and the retained ideality factor is at least one. The logarithmic inverse requires I > −Is.
- Reverse bias approaches −Is; voltage and current may be signed. Zero voltage gives zero current but cannot determine Is, n or Vt uniquely.
- Enter known quantities and leave the unknown blank. Editable quantities support inverse solutions and locks; inconsistent locked quantities are reported. Unit selectors convert the quantity independently of its display.
- Reviewed hash-pinned model correction: The model describes an ideal junction without series resistance, high-current effects or reverse breakdown. Saturation current and thermal voltage are positive, and the retained ideality factor is at least one. The logarithmic inverse requires I > −Is. Reverse bias approaches −Is; voltage and current may be signed. Zero voltage gives zero current but cannot determine Is, n or Vt uniquely. Enter known quantities and leave the unknown blank. Editable quantities support inverse solutions and locks; inconsistent locked quantities are reported. Unit selectors convert the quantity independently of its display.
Common questions
Can current be negative?
Yes. Reverse bias gives negative current approaching minus the saturation current; reverse breakdown is outside the model.
Does the equation include a resistor?
No. A real series resistor changes the applied-voltage relation and needs a separate circuit solution.
How do I use the inverse calculation?
Clear the quantity you want to find and enter the remaining known values in their selected units. The model can only solve branches with enough independent information.
References
Enforce the documented finite physical branch and inverse domains.