Apparatuses and methods are disclosed for controlling a multicolor LED array. The light engine includes a dimming emulator that supplies high and low supply voltages to a driver dependent on a duty cycle of PWM signals from a control unit. An optical coupler isolates the low supply voltage from ground of the dimming emulator. The control unit receives power for the array from the driver dependent on the supply voltages and controls the array based thereon. The coupler is coupled to a control terminal of an NPN transistor, the PWM signals change the average impedance of the coupler based on the duty cycle and change a voltage divider ratio applied to the control terminal. Other apparatuses and methods are disclosed.