R_int LED Simulation

QSPICE
1

I would like to simulate the LED with input voltage 5V. How to define the R_ser to achieve VF 3V since there is no information about the R internal of LED? Based on the forward voltage vs forward current, I think the internal resistor is depend on the forward voltage. For the example at VF 3V, R_int = 3/0.15 = 20 Ohm, then for my input 5V I should connect the R_ser = 13.3 Ohm. Please review my analysis and looking for your feedback all. Thank you.

example_led.qsch (2.2 KB)

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2

You should use a diode model for that. Have you considered using File > Model Generator > Diode to create a model based on your datasheet?

This .model from the Qspice Model Generator specifically models above I-V characteristic

.model DUT D Is=3.820663e-26 N=1.88179 Rs=1.79 XTI=52.0773
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3

It is really good. Thank you Kelvin.

1 Like