Hi TI,
I'm testing with TLC5947 IC if it's possible to use several LEDs in series.
when I set the LED voltage (VCC of above circuit), the criteria is ['Vf(max) of LED' x 'number of LEDs']. (the target voltage of LED)
The existing application used only 1 LED, so there was no heating issue.
But at this project, I'd like to use 4 LEDs in series, and the temperature of TLC5947 IC is over 100℃.
So I decreased the target voltage step by step from (3.7V x 4 = 14.8V) to 11V, then the temperature was about 50~60℃.
-> the measured voltage of 4 series LEDs is 11.2V // so I think the other 3.5V is the root cause of heating.
when I use just one LED, the voltage gap is about 1V, but the gap may multiply by number of LEDs, and turn up the heat.
The problem solved when I measure the real voltage and set the target voltage lower, however if we meet the wide Vf LED, then the LED would not work.
Is there any solution or idea that both set the LED target voltage normally and reduce the heat?
