The kind of nominal current sharing provided by the basic methods of paralleling supplies, with or without diodes, is called droop sharing. The accuracy is crude, and not guaranteed over supply differences. There are two active methods of current sharing. The first one, shown on this slide, has the Current Sharing Controller, the CSC, adjusting the power supply voltages based on the current contributions. For example, a power supply with lower current would be adjusted up in voltage to increase its share till both inputs to the CSC are equal. Accuracy is much better, depending on CSC input offset and sense resistor matching. Access to the power supply is required and the supply itself needs features such as trim pins or feedback networks that allow on-the-fly adjustment of its output voltage. Designing the control loop for this method requires studying the power supply loop dynamics, which in turn makes the design intimately tied to that particular supply. The design would have to be redone if a different supply type was substituted.