What this N-channel MOSFET does in the circuit
The IRFR4105TRPBF is a 55 V, 27 A N-channel HEXFET MOSFET in a DPAK (TO-252) surface-mount package, designed for low-voltage switching in power supplies, DC-DC converters, and motor drives.
At 27 A the actual on-resistance will be higher due to self-heating, so budget the conduction loss using the typical Rds(on) vs temperature curve in the datasheet.
Temperature range and package — field-swap reality
On a rework station you can swap it in the field with a hot-air pencil; just pre-tin the pad and watch the tab solder joint.
