Power 5630 LEDs without resistors using AMC7135 LED driver

[hans_magnus]

@ggf31416

I have no experience at all designing circuits, take what I say with a grain of salt. If you put a resistor between the 7135 and the LEDs it only needs to be big enough to stabilize the current so if a LED wants to take 300mA instead of 120 at the average vF it will reduce it’s voltage a bit, let’s say 0.1v, so it won’t take that much current. You don’t need it to drop 4.2V to 3.4V, that’s the 7135’s job. How much resistance is needed would depend on the variation on the LED’s vF curves, sometimes just the circuit resistance is enough but I think the 5630 may be more fragile than the high power LEDs we are used to.

If only 3 LEDs are sharing each 7135 I think the problem should be reduced, beyond limiting the max current to 350mA, if a LED is ‘greedy’ it should take less current when the total is 350mA than if all the LEDs share the full current.

Perfect!

So the AMC7135 can do the voltagedrop-job, nice! Thanks!

And thank you everyone for highlighting that a broke LED will result in higher current through the remaining LEDs