I'm designing an aluminum PCB containing a series of 1W LEDs. The series of LED will be powered by 24VDC and N-MOSFETs will be placed between the ground and every series of LEDs. The gates will be attached to Arduino PWM pins.
Here is the example schematic:
The number of LEDs in a series is determined by dividing the 24VDC with the forward voltage of each LED. For example, the white LED has a forward voltage range of 2.8-3.4V and a forward current of 350 mA. Dividing the 24V by the forward voltage, I can have 8 white LEDs in series. Now the question is do I still need the resistor added in the series or is the number of LEDs enough to limit the current to around the 350 mA range?