Milpitas, Calif. - Linear Technology's LTC4354 is a -48 volt diode-OR controller chip for high availability systems. It meets the requirements of the AdvancedTCA telecom spec. With the LTC4354, users control two external N-channel MOSFETs in the redundant supply paths instead of traditional OR-ing diodes (which have a higher voltage drop) to dramatically improve efficiency and eliminate bulky heat sinks. The IC is available in a 2-by-3 mm DFN package.
Operating with supply voltages up to -80V, the LTC4354 turns off the appropriate MOSFET in less than 1 microsecond if either power supply fails. An open-drain fault output, capable of driving an LED or opto-coupler, indicates if either FET has excessive voltage drop. This occurs if the FET or series fuse has gone open or if there is a supply overload.
The controller is rated for operation over the commercial and industrial temperature ranges. It is also available in an SO package. Pricing begins at $1.95 each in 1k quantities.