The LTC4359 is an ideal diode controller with reverse input protection. When two LTC4359 controllers are used for ORing different voltage sources (e.g., 60V and 24V), a significant VIN undershoot during transition or heavy load can cause the controller to interpret the condition as a reverse current event.
Here’s why:
The LTC4359 actively monitors the voltage difference between IN and OUT pins. If VIN drops far enough that OUT is higher than IN (or close to it), the controller quickly turns off the MOSFET to block reverse current flow. This is part of its fast turn-off feature designed to minimize reverse current transients when a source fails or is shorted.