What are the concerns when connecting LEDs in parallel?
The forward voltage of LEDs varies from LED to LED. LED forward voltage increases with an increase in forward current. When LEDs are connected in parallel, the voltage drop across each LED is identical. However, different amounts of current are needed to achieve the same forward voltage drop. Thus, an LED with a lower forward voltage will need more current than an LED with a higher forward voltage. This difference in forward current will cause a difference in intensity. In some cases this difference is objectionable. Therefore, each LED should have its own current limiting resistor.
