PI2007D3-EVAL1: 12A Or-ing for 48V Systems

The Active ORing circuit in Figure 2 uses both the PI2003, to control the low-side MOSFET, and the PI2007, to control the high-side MOSFET. Since Active ORing components are not designed to enhance current sharing between the supplies, one of the supplies will dominate and provide the current to the load. The PI2003 has a low-current fault feature that is used to either enable or disable the PI2007 associated with it. If there is little or no current through the PI2003 it issues a fault condition that pulls its FT pin low.

The MOSFET that is used to provide a return path for the PI2007 bias supply is then disabled, which in turn disables the PI2007. If the input supply is still in-circuit, then the PI2003 will remain powered up and will continue to monitor the supply. If the supply were to be removed or disabled, then the supply to the PI2003 would be discharged and the PI2003 would disable its MOSFET. The resulting circuit would be just the two parasitic body diodes of the high and low side MOSFETs.