Hello,
I am working with LM3435 eval board with OSRAM RGB LEDs LRTB C9TP series.
I connected 5 such LEDs in parallel and re-tuned the current setting resistor to 750mA. The LEDs have Vf of 2.1, 3.4 and 3.3V for R,G,B respectively at If = 140mA. With 5 in parallel, current sourced to each LED is 150mA.
Now the problem is, only red light is working but not green and blue. With a transition delay of 35usec, LM3435 output is supposed to adjust to Vf for each LED but looks like it is not or I am missing something.
To confirm this, I controlled only RED LEDs with RCTRL and found that Vf is ~7.0V and is changing with change in I/p Voltage and the same for green LEDs also.
LM3435 datasheet says that Vout-Vin for RGB is 2.4V, 3.3V and 3.3V respectively. Is that a mandatory condition in which case, with Vf required for RGB leds, and min and max Vin to LM3435, it will be impossible to meet that criteria.
Please advise where I went wrong.