Such isolation from supply failure is provided by series diodes in the power path. The diode will reverse bias and open up when one supply goes down, preventing current flow in the reverse direction. This is commonly referred to as diode-ORing the supplies. The supply current characteristic of a diode-OR vs. supply voltage difference is shown to the right. For large differences, the highest supply wins, providing all the load current. When the supplies are close together, typically within tens of millivolts, the two supplies will share some of the load current; the slope of the currents in the transition region depends on the path resistances.