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[LTSpice] Simulate Led Strip

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lfaborges:
Hello friends.

I'm trying to simulate on LTSpice, a led strip I bought.



Voltage: 12V
Power: 10W / m
White Leds: 120 leds / m
Color Temp.: 4000K

I'm going to use 4.4m (44W -528 leds).

How do I simulate this in LTSpice?

Thanks :)

OM222O:
1) Why would you want to simulate a led strip in ltspice?

2) you can use a constant current sink attached to a 12v source and make it draw the right amount to be 44watts, which is not very useful?

3) you can also use a diode + small value resistor to allow a large current to pass through, still not ideal / useful?

Jay_Diddy_B:
Hi,

The answer is like this:



I have explained how this works on the model.

I have attached the LTspice model.

Regards,
Jay_Diddy_B

 LED strip model.asc (1.06 kB - downloaded 318 times.)

Ian.M:
You don't have enough data, but we can make some assumptions.
To simulate it accurately you'd have to know the Vf of the individual LEDs (and at what If), and the value of the series resistor for each string of three LEDs.

From the specs you've given, the If per LED must be approx 20.8 mA ( (10W/12V)/(120/3) ).  From that and the Vf at that current, you can work out the dropper resistor for each string of three LEDs.   

For the actual modelling Jay_Diddy_B has already posted a solution that's better than mine.

Jay_Diddy_B:
Hi,

Ian.M +1

There is not enough information to make an accurate model.

It looks from the photo that the Resistor is marked 101 which is 100 \$\Omega\$. This is the easy part.

The resistor could also be 181 which is 180 \$\Omega\$. It is hard to see from the photo.

I just used the LED in the library. To improve the accuracy of the model you have to measure the VI characteristics of a section of the tape.

An LED model can be created so that the VI curves of the model and the hardware match.

Jay_Diddy_B

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