The easiest way to illustrate how crossplexing works is shown with two LEDs and two I/Os. Putting a voltage on one I/O (red) and ground to the other (black) either the left or the right LED will be lit. So one LED is driven normally while the other one is operated reverse, which in fact blocks any current flow. If the I/Os are switched now very fast it seems that booth LEDs are lit. If the duty cycle is 50% and the current is 100mA the average current through the LED will be 50mA. Adding another I/O enables the circuit to drive six independent LEDs as show in the right hand example on this slide. Again, as the sink cycles through the available I/Os quickly, only the LEDs connected to the sink via their cathode can be driven now. In the upper diagram, users can see the two LEDs in yellow which are be enabled in that configuration. Both, only one or none of the LEDs can be turned on at this time. This depends in the sources (shown in red) being active or off. Again if the total current is 100 mA the average current on the LEDs will be 33mA.