ISL644

Data Sheet October 6, 2011 ISL6144 FN9131.7 High Voltage ORing MOSFET Controller The ISL6144 ORing MOSFET Controller and a suitably sized N-Channel power MOSFET(s) increases power distribution efficiency and availability when replacing a power ORing diode in high current applications. In a multiple supply, fault tolerant, redundant power distribution system, paralleled similar power supplies contribute equally to the load current through various power sharing schemes. Regardless of the scheme, a common design practice is to include discrete ORing power diodes to protect against reverse current flow should one of the power supplies develop a catastrophic output short to ground. In addition, reverse current can occur if the current sharing scheme fails and an individual power supply voltage falls significantly below the others. Although the discrete ORing diode solution has been used for some time and is inexpensive to implement, it has some drawbacks. The primary downside is the increased power dissipation loss in the ORing diodes as power requirements for systems increase. Another disadvantage when using an ORing diode would be failure to detect a shorted or open ORing diode, jeopardizing power system reliability. An open diode reduces the system to single point of failure while a diode short might pose a hazard to technical personnel servicing the system while unaware of this failure. The ISL6144 can be used in 9V to 75V systems having similar power sources and has an int...