I've been trying to design a circuit to control 23 LEDs dimming using a LED driver, but I don't quite understand how they work. Put for example the model BCR420/1:
Datasheet: BCR420/1 Datasheet
I have 23 LEDs to control, with
Vf = 3.3V and
If = 30mA.
If I wanted to control all 23 LEDs in a single string, It would require
Vs to be at least
Vs = 1 (voltage drop of the IC) + 3.3*23 = 76.9V, which is too much.
Now, I could use two alternatives:
- Use several LED drivers to control fewer LEDs.
- Use parallel strings with several LEDs in each one.
In case of using parallel strings, it would require
Iout = 30mA * Number_of_strings and then I'd have to make sure the string with uneven LEDs had the appropriate voltage. But how could this be done? What's the real meaning of
So my main questions are:
- What is the meaning of
- Could I use several strings of LEDs instead of an LED driver for a set number of LEDs?
- If I used several drivers, could the same PWM signal be used for all of them?