WHY: Provide diode protection without the significant voltage drop of a traditional diode which becomes significant at higher currents. This implementation uses a MOSFET which switches on when the current flow in the desired direction and switches off the MOSFET before the current flow becomes negative which is a achieved by controlling for a 22mV drop across the body diode of the MOSFET.

USE: For use where diodes are required to block reverse current flow, especially in high current (>1A applications).

MODULARITY: The module can be used to replace a traditional diode with minimal voltage drop and operates independent of other circuit elements.

FEATURES & SPECIFICATIONS: Maintains a constant 22mV across the body diode of the MOSFET for inputs < 75V (100V transients) and current < 30A DC.

APPLICATIONS: Power supply Oring, solar regulator reverse flow blocking, PSU / battery chargers.

DESIGN CHOICES: Designed to support high current applications (up to 30A). Both terminal and direct wire connections are supported. Input clamping diode to prevent large negative voltages during high current shutdown. Input and output capacitors implemented for stability.

CALCULATIONS / CONSIDERATIONS: The MOSFET needs to have as low as possible Rds on to reduce loss. However, this is typically coupled with higher gate capacitance and therefore slower discharge (longer off delay). Furthermore, a very low Rds on will reduce the sensitivity to reverse flow. Therefore, it's a balance depending on the application.

TESTING: No measurable temperature rise with a constant 20A current.

FINDINGS: Can be sensitive to severe AC noise.

IMPROVEMENTS & NEXT STEPS: Consider a higher voltage rating for the MOSFET for greater short circuit survivability of transients (e.g. AGM20T09LL from the current HYG015N10NS1TA). Note the suggested MOSFET has a higher Rds on resistance and therefore will also improve controllability. Also consider an appropriate TVS diode on the output to clamp transients

References: LM5050-2 High Side OR-ing FET Controller datasheet (Rev. B) (ti.com) 

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