For light loads, the MAX5943A is designed to turn off Q1 and allow current to flow through the body diode, but Q1 can be kept ON even with a light load by driving the ONQ1 input high with an external control signal.
One method to drive the ONQ1 input high during light loads is to connect a current-sense amplifier to the high-side sense resistor (between IN and SENSE), and feed its output to a window comparator that will force ONQ1 high when the current is low but not the reverse. At higher current, the signal will rise outside the window and the normal MAX5943 thresholds can take over again. Hypothetically one could use the external signal and single-threshold comparator to control all aspects of the ORing function through the ONQ1 input.
Alternatively, depending on the application voltages, one could consider the more recent MAX15068, which has lower reverse-current detection thresholds and active control of the forward “ideal diode” voltage drop, improving efficiency compared to the older MAX5943 product. Here are some general reasons to consider the MAX15068 over the MAX5943.
Higher gate drive improves pass-FET Rds(on): +11V
ORing function: active regulation of VDS at -10mV as opposed to hysteretic on-off
ORing function: fast turn-on at VDS = -80mV, reverts to active regulation at -40mV
Circuit-Breaker threshold: more efficient at 35mV minimum setting
Fold-back current limit on startup