48V Ideal Diode-OR Controller Provides Higher Efficiency &

The LTC4355 dual ideal diode-OR controller from Linear Technology allows Schottky diodes to be replaced by N-channel MOSFETs in high availability systems and provides extensive fault monitoring to diagnose supply failures. Forming the diode-OR of input supplies in this manner reduces power consumption, heat dissipation and PC board area. The wide operating range of 9V to 80V supports diode-OR applications with two positive supplies, such as a 12V distributed bus architecture or the return paths of two negative supplies, as in -48V AdvancedTCA (ATCA) applications. Additionally, the LTC4355 monitors and separately signals several types of faults: if the input supplies are not in regulation, if the inline fuses are blown, or if the voltages across the MOSFETs are greater than the fault threshold.

In high power, high availability applications such as ATCA, where redundant supplies and redundant returns are mandated, the power and heat dissipation of OR-ing diodes can be excessive and therefore MOSFETs provide a more efficient solution. The LTC4355 provides the gate drive for external N-channel MOSFETs, fast turnoff to prevent reverse current and smooth switchover between supplies without oscillation. The LTC4355 positive diode-OR controller complements the LTC4354 negative diode-OR controller, as well as Linear's extensive family of Hot Swap™ controllers, including the LTC4252A with tight UV/OV tolerance and the LTC4261 with an internal ADC for extensive monitoring.

Specified over the commercial and industrial temperature ranges, the LTC4355 is offered in 4mm x 3mm 14-lead DFN and 16-lead SOIC packages. Available from stock, pricing begins at $2.50 each in 1,000 piece quantities.