What this OptiMOS N-channel switch brings to the board
The Infineon BSC042N03MSGATMA1 is a 30 V N-channel MOSFET from the OptiMOS series. Its maximum on-resistance is 4.2 mOhm at a 10 V gate drive with 30 A of drain current.
Package and mounting — the thermal path is the spec
The 8-PowerTDFN package (Infineon code PG-TDSON-8-5) is a surface-mount power package with an exposed drain pad on the bottom. That pad is the primary thermal path — solder it to a copper plane on the PCB with multiple vias to inner layers. The ±20 V maximum gate-source rating gives headroom for gate-drive transients, but the threshold voltage of 2 V at 250 µA means it starts turning on well below 5 V logic levels. Input capacitance of 4300 pF at 15 V is typical for this on-resistance class; the gate driver sees that as the load per switching edge.
Lifecycle and sourcing posture
The BSC042N03MSGATMA1 carries an Active product status and ROHS3 compliance from Infineon. There is no announced end-of-life or last-time-buy window. No direct pin-compatible second source appears in the record — the IPD50R950CEAUMA1 is a 500 V CoolMOS device in a different package, not a functional substitute for this 30 V part.