6.7 Current-Sharing Circuit

The figure below allows two MIC38300 regulators to share the load current equally.

Figure 6-2. Current-Sharing Circuit for 6A Output

Regulator #1 senses the output voltage at the load, on the other side of a current sense resistor. As the load changes, a voltage equal to the output voltage, plus the load current times the sense resistor, is developed at the V_OUT terminal of Regulator #1. The op-amp (MIC7300) inverting pin senses this voltage and compares it to the voltage on the V_OUT terminal of Regulator #2.

If the current through the current sense of Regulator #2 is less than the current through the current sense of Regulator #1, the inverting pin will be at a higher voltage than the non-inverting pin and the op-amp will drive the FB of Regulator #2 low. The low voltage sensed on Regulator #2 FB pin will drive the output up until the output voltage of Regulator #2 matches the output voltage of Regulator #1. Since V_OUT will remain constant and both regulator V_OUT terminals and sense resistances are matched, the output currents will be shared equally.