Automotive-grade 70V rail clamp in a SMB footprint
The SMBJ70AQ-13-F: Its 70V reverse standoff voltage (77.8V min breakdown) and 113V clamping at 5.3A (10/1000µs pulse) make it a direct fit for clamping 48V or 70V nominal rails in engine-control units, battery-management systems, and ADAS sensor power feeds. The -55°C to +150°C junction-temperature range covers the full under-hood thermal profile, and the unidirectional single-channel design protects one rail per device.
The 600W peak-pulse power (10/1000µs waveform) is the device's energy-handling ceiling at 25°C. For a 70V rail, the 113V clamping voltage means the protected circuit sees a maximum transient of 113V before the TVS conducts — well within the 150V abs-max of most 70V-rated downstream ICs and MOSFETs. The 5.3A peak-pulse current at that clamping voltage is the current the diode must sink during the transient. A 70V rail with a 10-ohm source impedance delivers 4.3A into a 113V clamp — the diode has 1A of headroom before exceeding its rated Ipp. No power-line protection (the diode is unidirectional and not designed for AC line clamping) — it clamps only one polarity, which is standard for DC rail protection in automotive and industrial 48V/70V buses.
Package and board-fit — DO-214AA SMB
The DO-214AA (SMB) package shares the same footprint as the smaller DO-214AC (SMA) and larger DO-214AB (SMC) — the pad geometry is identical across the family, so a single PCB layout can accommodate any of the three by swapping the reel. The SMB body is 4.6 mm long × 3.6 mm wide, with a 2.3 mm cathode-tab width that carries the thermal path to the board. The tape-and-reel packaging (13-inch reel, 3000 pieces typical) feeds directly into pick-and-place lines without a reel change.