Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Reference Amperes (A)

Required number input.

Temperature Celsius (°C)

Required number input.

Reference Celsius (°C)

Required number input.

Doubling Degrees Celsius (°C)

Required number input.

Empirical dark-current estimate from a measured reference current and an assumed doubling interval in temperature. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Dark Amperes (A)

The resulting dark amperes returned as a number.

• Photodiode and phototransistor current depend on wavelength, optical power at the active area, responsivity, bias, gain, temperature, dark current, bandwidth, and load. Shot noise, amplifier noise, saturation, and optical coupling are separate design constraints.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• APD Gain

  Calculate avalanche photodiode current multiplication from multiplied photocurrent and unity-gain primary photocurrent after dark-current subtraction.

• Battery Internal Impedance

  Estimate DC battery internal resistance from the voltage drop between two load-current operating points measured over a short interval.

• Laser Threshold Temperature

  Empirical laser threshold-current temperature dependence I(T)=Iref exp((T−Tref)/T0).