7.1 Overview

Blocking diodes are commonly placed in series with supply inputs for the purpose of ORing redundant power sources and protecting against supply reversal. The LM5050 replaces diodes in these applications with an N-MOSFET to reduce both the voltage drop and power loss associated with a passive solution. At low input voltages, the improvement in forward voltage loss is readily appreciated where headroom is tight, as shown in Figure 2. The LM5050 operates from 5 V to 75 V and it can withstand an absolute maximum of 100 V without damage. A 12-V or 15-A ideal diode application is shown in Figure 24. Several external components are included in addition to the MOSFET, Q1. Ideal diodes, like their non-ideal counterparts, exhibit a behavior known as reverse recovery. In combination with parasitic or intentionally introduced inductances, reverse recovery spikes may be generated by an ideal diode during an reverse current shutdown. D1, D2 and R1 protect against these spikes which might otherwise exceed the LM5050 100-V survival rating. COUT also plays a role in absorbing reverse recovery energy. Spikes and protection schemes are discussed in detail in the Short Circuit Failure of an Input Supply section.