M3966m Mosfet Verified ~repack~ Official

The marking “M3966M” seen on small QFN/PDFN MOSFETs used in laptop and GPU VRAM power circuits most commonly corresponds to the UBIQ (or OEM-labeled) QM3966 family (examples: QM3966M3, QM3966M6). These are N‑channel power MOSFETs in compact packages (PDFN/QFN variants) rated for low voltage (≈30 V) and designed for synchronous buck switching in high-current, space-constrained applications (VRAM/GPU VR rails, CPU/GPU power stages).

| Replacement Part | Reason | | :--- | :--- | | | Widely available, 60V, 0.3A, RDS(on) ~2Ω – best substitute | | BSS138 | 50V, 0.22A, RDS(on) ~3.5Ω – good for lower current | | MMBF170 | 60V, 0.5A, RDS(on) ~5Ω – closest match | | AO3400 | 30V, 5.8A – only if voltage is 30V, not 60V | m3966m mosfet verified

When replacing this on a PCB, use a hot air station set to 380°C. The ground plane wicks heat fast; pre-heat the board to avoid ripping the pads. The marking “M3966M” seen on small QFN/PDFN MOSFETs