What this ORing controller does in the rail
The LTC4359IS8#TRPBF is an N+1 ORing controller from Analog Devices that drives an external N-channel MOSFET to emulate a Schottky diode with a much lower forward voltage drop. It manages the connection of multiple power supplies to a common load rail, allowing seamless N+1 redundancy without the heat and voltage loss of a discrete diode. The controller does not integrate the power switch — it drives an external N-channel MOSFET, giving the designer flexibility to size the pass element for the specific load current and thermal budget.
Asymmetric delay: fast block, slow engage
The critical timing spec is the 300 ns off-delay — when the input supply droops or fails, the controller turns off the external MOSFET in 300 ns, blocking reverse current from the output capacitor or the redundant supply back into the failing rail. That fast response prevents bus collapse and keeps the load powered without interruption. The 200 µs on-delay is deliberately slow: it prevents the MOSFET from turning on during the initial power-up transient or during a brief input glitch, avoiding a current surge that could pull down the shared rail. Supply current is 150 µA — low enough to keep the controller alive on the output rail even when its own input supply is absent, which is the typical ORing topology.
Where it fits: redundant supplies and automotive
Application targets include automotive electronics (ECUs, infotainment, ADAS power distribution), redundant power supplies for servers and base stations, and telecom infrastructure where dual-feed or battery-backup ORing is required. The N:1 input-to-output ratio means it can handle multiple input feeds (N) to a single output rail — the controller selects the highest-voltage input and blocks the rest, with the fast off-delay catching any supply that drops.
Package and footprint
The supplier device package is 8-SO — a standard footprint shared with many other ORing controllers and op-amps, making board layout reuse straightforward.
Lifecycle and sourcing posture
It is ROHS3 compliant.