A dual mode constant output current LED driver is capable of operating with a very wide range of input direct current (DC) voltage. This provides an effective topology for a wide range of constant output current LED drivers, and allows for changing the number of connected LEDs without negatively impacting the output current. The LED driver includes a converter and a mode selection circuit that control the modes of the circuit based on the voltage. The converter and mode selection circuit operate in a buck-boost mode when the output voltage of the LED driver is less than the DC input voltage plus a first threshold amount, and in a boost mode when the output voltage of the LED driver is greater than the DC input voltage plus a second threshold amount.