N+1 ORing controller for 2.5V to 80V rails
The LTC4373IMS8#PBF is an N+1 ORing controller from Analog Devices that drives an external N-channel MOSFET to create an ideal-diode function for redundant power supply architectures. It operates from a 2.5V to 80V supply range, covering 3.3V logic rails through 48V telecom buses and 12V/24V automotive systems. The controller uses a 500 µs turn-on delay to let the incoming supply stabilise before connecting the load, and a 500 ns turn-off delay to prevent reverse current during source transients.
5 µA quiescent current — always-on without thermal penalty
The standout parametric on this part is the 5 µA supply current — an order of magnitude below typical ORing controllers that draw tens to hundreds of microamps. This matters for always-on redundant supplies where the ORing controller sits powered even when the main converter is off. In a 48V telecom system, 5 µA translates to 240 µW of standing loss per controller, negligible in the system thermal budget. The 10 µA maximum output current from the gate drive is sized for the external N-channel MOSFET's gate charge, not for driving a load directly.
Automotive and redundant supply applications
The 80V absolute maximum input covers 24V truck systems with load-dump transients, though the nominal operating range is 2.5V to 80V. The 8-MSOP package (3.00 mm width) keeps the board footprint small — useful when placing one controller per redundant rail in a multi-rail ORing array.