Active Oring Solutions Reduce Power Losses, Size

摘要

An active ORing solution combines a power MOSFET and a controller IC. The MOSFET has an on-state R_(DS(on)) characteristic that, when multiplied by the square of the current through the device, creates power loss in the MOSFET. This loss can be up to 10x lower than the power loss of a Schottky diode ORing solution for the equivalent current. That means an active ORing solution can be much smaller than a standard ORing diode solution because of its low power dissipation and much reduced dependency on thermal management. However, active ORing does have tradeoffs. A MOSFET, when it is turned on, allows current to flow in either direction through its channel. Because of this it is essential that the active ORing solution be very accurate and capable of extremely fast detection of reverse current fault conditions. Once the fault has been detected, the controller is required to turn off the MOSFET as fast as possible, and thus in turn isolate the input fault from the redundant bus and prevent any further reverse current.