how much should the V_led exceed the forward voltage of the led?
Does the TLC need some control reserve?
I tried to figure it out with the datasheet but i could not found it.
with best regards,
René
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Hello Rene,
Figure 5, OUTPUT CURRENT vs OUTPUT VOLTAGE graph shows how much output voltage TLC5940 needs.
If you want to set the output current to 60mA, then I would recommend you to set output voltage 0.8~1.0V.
The output voltage is determined by LED forward voltage and LED power supply voltage like the following equation.
VOUT = VLED - (Vf * N)
Where: VLED = LED lamp power supply voltage, Vf = LED lamp forward voltage at the current, N = the number of LED lamp connected in series.
So if you use 2 LED in serise at 60mA and LED maximum forward voltage is 3.5V, then the LED power supply voltage should be set to the following
VLED.
VLED = VOUT + (Vf * N) = 1V + (3.5V * 2) = 8.0V.
Best regards,
Kazuya.Nakai
Hello Rene.
3.3V curve are almost same as 5V. But the maximum output current in 3.3V is 60mA.
Best regards,
Kazuya Nakai.