9 mOhm at 30 A — the conduction-loss anchor for a synchronous buck
The BSC889N03LSG: 9 mOhm maximum on-resistance at 30 A drain current with 10 V gate drive. 16 nC total gate charge at 10 V.
Dual current rating — the thermal interface decides the real limit
The datasheet lists 45 A continuous drain current at the case temperature (Tc) and 13 A at ambient (Ta). That spread tells you the silicon can handle 45 A if the exposed pad on the PG-TDSON-8 package is soldered to a large copper plane on a multi-layer board. At 13 A ambient with 2.5 W dissipation (Ta rating), the junction stays below 150 °C only if the board copper does the heatsinking. The 28 W case-power limit assumes a heatsink or chassis contact — without it the thermal impedance through the PCB dominates.
Gate drive window and switching behaviour
Drive voltage range of 4.5 V to 10 V for achieving the rated Rds(on). At 4.5 V the on-resistance will be higher than the 9 mOhm figure — the 10 V drive is the condition for the minimum Rds(on) spec.
Package and footprint — PG-TDSON-8
The 8-PowerTDFN (PG-TDSON-8) is a surface-mount package with an exposed drain pad on the bottom.
Lifecycle and compliance
It is ROHS3 compliant. Sourcing is through standard independent distribution channels, quoted to order against the BOM quantity.