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Diode-OR controller reduces power consumption, voltage loss

Milpitas, Calif. — Linear Technology offers the LTC4357, a single high-voltage ideal diode-OR controller, as a low loss replacement for Schottky diodes in N+1 redundant power supply applications and high-availability systems.

The LTC4357 device's wide operating range of 9 V to 80 V supports diode-OR applications with two positive supplies such as a 12-V distributed bus architecture or the return paths of two negative supplies such as in -48-V AdvancedTCA (ATCA) applications. The LTC4357 tolerates fast dV/dt transients during insertion, providing immunity to latchup.

The LTC4357 controls an external N-channel MOSFET to perform the function of a low forward voltage diode. This provides a lower loss path compared to the Schottky diode that, in high power applications, not only provides a more efficient solution but saves board area by eliminating the need for heat sinking. The LTC4357 controls the forward voltage drop across the MOSFET to ensure smooth switchover from one path to another without oscillation or reverse DC current. In addition, the device is said to reduce power consumption, heat dissipation and voltage loss.

The LTC4357 can be used in applications where multiple power supplies are paralleled to provide load-sharing. In N+1 redundant systems, an additional supply is added to safeguard the system in the event one of the N supplies fail. If the power source fails or is shorted, the LTC4357 ensures a fast 0.5 us turn-off to minimize reverse current transients. The LTC4357 can also be used to safeguard against reverse voltage events, providing reverse input protection to downstream electronics.

In addition, the LTC4357 can be configured with a hot-swap controller and hold-up capacitor to provide input supply hold-up for a period of time after a loss of input power. This enables continuing system operation without resetting or rebooting due to brief interruptions of input power. Specified over commercial and industrial temperature ranges, the LTC4357 is offered in 2 x 3-mm 6-lead DFN and 8-lead MSOP packages.

Pricing: Starts at $1.70 each in quantities of 1,000.

Product information: LTC4357

Linear Technology Corp. , 1-408-432-1900, www.linear.com

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